The work of a student to solve a set of equations is shown:
Equation A: y = 10 - 22
Equation B: 5y = 2 - 4z
Step 1: -5(y) = -5(10 – 2z) [Equation A is multiplied by -5.]
5y = 2 - 42 [Equation B]
Step 2: _5y = 10-22 [Equation A in Step 1 is simplified.]
5y = 2 - 4z [Equation B]
Step 3:
0 = 12 - 6 [Equations in Step 2 are added.]
Step 4:
z = 12
Step 5:
z = 12
In which step did the student first make an error?

Answers

Answer 1

Answer:

Step 2.

Step-by-step explanation:

Given the two equations,

Equation A: y = 10 - 2z

Equation B: 5y = 2 - 4z solved by a student, we are to determine the step where the student made an error in his/her calculation. Let's follow the steps;

Step 1: multiply equation A by -5. The essence of this is to be able to cancel out one of the variables and calculate for the other variable. On multiplication we have;

y = 10 - 2z × (-5)

5y = 2 - 4z × (1)

_____________________

-5y = -5(10-2z) .... A

5y = 2 - 4z..... B

Step 2: simplify equation A by opening the bracket.

-5y = -5(10)+5(2z)

-5y = -50+10z

The equations become;

-5y = -50+10z .... A

5y = 2 - 4z..... B

It can be seen that her simplified expression does not tally with what we got i.e -5y = -50+10z. This was the step the student made the first error.

Since this student step is wrong, the remaining calculation will be wrong.

Let us fix the calculation steps now.

We will continue from the previous step.

Step3: Add equation A and B in step 2 together.

-5y+5y = (-50+2)+(10z-4z)

0 = -48+6z

Step 4: Add 48 to both sides:

0+48 = -48+6z+48

48 = 0+6z

48 = 6z

Step 5: Divide both sides by 6

48/6 = 6z/6

6 = z

z= 6

Hence, the value of z = 6 not 12 and the student made his/her first error in step 2.


Related Questions

What is x in the diagram below?

Answers

Answer:

3rd option, 2√10

Step-by-step explanation:

x²=4×10

or, x=√(4×10)

or, x=2√10

Answer: C, 2√10

Step-by-step explanation:

Isabelle bought some stationery. 1/3 of them were pencils. 5/8 of the remainder were erasers and the rest were ruler.The cost of the stationery is ,Pencil: $1.20 ,Eraser :$1 ,Ruler: $0.50 She spent a total of $169.50 on all the stationery. How much more did she spend on erasers than rulers.

Answers

Answer:

She spend[tex]\frac{7}{24}[/tex] more on erasers than rulers.

Step-by-step explanation:

We are given that Isabelle bought some stationery.

Fraction of pencil = [tex]\frac{1}{3}[/tex]

Remaining stationary =[tex]1-\frac{1}{3}=\frac{2}{3}[/tex]

5/8 of the remainder were erasers

So, part of eraser in stationary=[tex]\frac{5}{8} \times \frac{2}{3}=\frac{5}{12}[/tex]

Remaining stationary(rulers)=[tex]\frac{2}{3}-\frac{5}{12}=\frac{1}{4}[/tex]

Cost of ruler = $0.50

Cost of [tex]\frac{1}{4}[/tex]rulers =[tex]0.50 \times \frac{1}{4}=\frac{1}{8}[/tex]

Cost of eraser=$1

Cost of [tex]\frac{5}{12}[/tex] eraser=[tex]\frac{5}{12}[/tex]

Difference in cost of eraser and rulers =[tex]\frac{5}{12}-\frac{1}{8}=\frac{7}{24}[/tex]

Hence She spend[tex]\frac{7}{24}[/tex] more on erasers than rulers.

Write the equation of the line that passes through the points (-3, -3) and (8,7). Put your answer in fully reduced point-slope form, unless it is a vertical or horizontal line.​

Answers

Answer:

Step-by-step explanation:

First you want to find the slope

y2-y1/x2-x1

7-(-3)/8-(-3)

Two negatives equal a positive. so Rewrite

7+3/8+3

10/11

Slope=10/11

To find the equation of the line..

y-y1=10/11(x-x1)

y-(-3)=10/11(x-(-3)

Again double negative, so rewrite

y+3=10/11(x+3)

y+3=10/11x+30/11

Subtract three from both sides to isolate 'y'

y+3-3=10/11x+30/11-3

y=10/11x+30/11-3

y=10/11x-3/11

Un ingeniero civil a cargo de una obra contrata una cierta cantidad de obreros. Estima que, si le

pagara S/ 1.400 a cada uno de los obreros, le faltarían S/ 8.000, pero si le pagara S/ 1.200 a cada

uno, le sobrarían S/ 2.000. El número de obreros que contrató es

Answers

Al plantear un sistema de ecuaciones lineales, encontramos que el número de obreros que contrató el ingeniero civil fue 50.

Para encontrar el número de obreros que el ingeniero contrató debemos plantear un sistema de ecuaciones lineales de dos ecuaciones con dos incógnitas, tal como sigue:

[tex] M - 1400*x = -8000 [/tex]   (1)

[tex] M - 1200*x = 2000 [/tex]   (2)

En donde:

M: es la incógnita igual al monto de dinero del ingeniero

x: es la incógnita igual al número de obreros

De la ecuación (1) tenemos:

[tex] M = 1400*x - 8000 [/tex]   (3)

Podemos encontrar el valor de x (número de obreros), introduciendo la ecuación (3) en la ec (2):

[tex] 1400*x - 8000 - 1200*x = 2000 [/tex]

[tex] 200*x = 10000 [/tex]

[tex] x = 50 [/tex]

El monto de dinero inicial del ingeniero sería entonces (ec 3):

[tex] M = 1400*50 - 8000 = 62000 [/tex]

Por lo tanto, el número de obreros que contrató el ingeniero es 50.

Puedes aprender sobre otro método de resolución de sistemas de ecuaciones lineales ingresando acá: https://brainly.com/question/10831551?referrer=searchResults                                    

                                                                                                   

Espero que te sea de utilidad!

ILL MARK BRAINIEST IF YOU DO THIS CORRECTLY!!!

Answers

Hmmm im on the same question so i think its this

This equation shows how the total number of necklaces Denise owns is related to the amount of money she spends on additional necklaces.

n = d + 74

The variable d represents the amount of money she spends on additional necklaces, and the variable n represents the total number of necklaces she owns. With $16 to spend on new necklaces, how many total necklaces can Denise own?

Answers

Answer:

16+74

Step-by-step explanation:

substitute 16 into the equation

Answer: n=90

d=16 so n= 16+74

please mark brainliest

9) A trapezoid has an area of 60 cm? and its height is 6 cm and one base is 8 cm.

Answers

Answer:

Step-by-step explanation:

Iihgghh

Any help? Khan Academy question

Answers

Answer:

1.6<x<9.6

Step-by-step explanation:

Triangle says the sum of any 2 sides is bigger than the third.

Assume a,b,c are side measurements of a triangle.

So if you know two sides a and b then the third number, c, is such that |b-a|<c<a+b.

So just add the given numbers and find the positive difference.

5.6+4=9.6

5.6-4=1.6

Assume all variables represent non negative numbers . Help please!!

Answers

Answer:

A). [tex]2p^{8}[/tex]

B). [tex]3m^{7}[/tex]

Step-by-step explanation:

A). [tex]\sqrt{4p^{16}}[/tex]

    To get the square root of the given expression we will convert it into the square form.

[tex]4p^{16}=(2)^2(p^{8})^2[/tex] [Since 2×2 = 4 and [tex]p^{8}\times p^{8}=p^{16}[/tex]]

Therefore, [tex]\sqrt{4p^{16}}=\sqrt{2^{2}\times (p^{8})^2 }[/tex]

                             [tex]=2p^{8}[/tex]

B). [tex]\sqrt{9m^{44}}[/tex]

    Since, [tex]9m^{14}=(3)^2\times (m^7)^2[/tex]

    Therefore,  [tex]\sqrt{9m^{44}}=\sqrt{(3)^2\times (m^7)^2}[/tex] [Since 3² = 9 and (m⁷)² = m¹⁴]

                                   [tex]=3m^{7}[/tex]

Line A has the equation: y = 2x + 5.
Determine the equation of line B when it is parallel to line A and passes through (0 , -4).

Answers

Answer:

y=2x-4

Step-by-step explanation:

The slope of the line is 2 and y intercept is - 4. The equation will be y=2x-4

What is the coefficient of x6 y4 in the expansion of (x + y)10?

Answers

Answer:

It is C.

Step-by-step explanation:

Too lazy to explain.

simplify (y+x) 2-2xy​

Answers

Answer:

y² + x²

Step-by-step explanation:

Given

(y + x)² - 2xy ← expand (y + x)² using FOIL

= y² + 2xy + x² - 2xy ← collect like terms

= y² + x²

Ans2x + 2y -2xy

Step-by-step explanation:

First You need to distribute 2 to both x and y. 2x + 2y-2xy

Please answer this in two minutes

Answers

Answer:

x = 16

Step-by-step explanation:

The figure shown shows an inscribed angle F and central angle E. Both angles intercept the same arc.

Therefore, angle E is twice the measure of angle F, according to the central angle theorem of a circle.

Thus,

m<E = 2 * m<F

(x + 94)° = 2(55)

We can find the value of x with this equation.

x + 94 = 110

Subtract 94 from both sides

x = 110 - 94

x = 16

1. Which expression is equivalent to (-2)(a + 6)?

Answers

Answer:

please mark my answer brainliest

Step-by-step explanation:

- 2a -12

Rachel's birthday party will cost $18 if she invites 6 guests. What is the unit rate?

Answers

Answer:

3

Step-by-step explanation:

Answer:

$3 per guest

Step-by-step explanation:

18/6

= 3

please help :) 1) Scientists develop knowledge by making blank about the natural world that may lead to a scientific question. 2) A scientific question may lead to a(n) blank , which can be tested. The results of blank can lead to changes in scientific knowledge.

Answers

Answer:

You just answered my question so you can ask yours, what a sped. Now i'm doing the same thing.

Step-by-step explanation:

You are setting out snacks for some friends to come over. You have 18 crackers and 12 slices of cheese. If you want each plate to be identical, with no food left over, what is the greatest number of plates you can prepare? How many crackers will be on each plate? How many slices of cheese will be on each plate?​

Answers

The concept of greatest common factor is used to solve this question. Then, we use it to find the number of crackers and slices of cheese, and the answer is:

The greatest number of plates you can prepare is 6.Each plate will have 3 crackers.Each plate will have 2 slices of cheese.

--------------------------------

To find the greatest number of plates, you need to find the greatest common factor between 12 and 18.

Thus, factoring them, always by the same number:

12 - 18|2

6 - 9|3

2 - 3

The greatest common factor is 2x3 = 6, which means that the greatest number of plates you can prepare is 6.

--------------------------------

18 crackers, so each plate has 18/6 = 3 crackers.

12 slices of cheese, so each plate has 12/6 = 2 slices of cheese.

A similar question is given at https://brainly.com/question/18454593

heeeellllp...

...

...

...

...

...

...

Answers

Answer:

didn't shade all of them

help w #5 !! will mark brainlist

Answers

The sum that represents the number of tickets sold if 35 tickets were sold Monday, half of the remaining tickets were sold on Tuesday and 14 tickets were sold on Wednesday.

To start solving this, we can assign t as the variable to the total number of tickets that were sold. So, t = 35 (for Monday) + (t - 35)/2 (for Tuesday) + 14 (for Wednesday). To solve this, we can say t = 49 + (t - 35)/2, or 2t = 98 + t - 35, which equals t = 63. Therefore, 63 tickets were sold total.

ASAP!!!!!!!!! PLEASE help me with this question! This is really urgent! No nonsense answers please.

Answers

Answer:

196 degrees

Step-by-step explanation:

360-164=196 degrees

the arch CDF=2*82=164

so the arch CGF =360-164=196 degrees

the probability that 2 randomly selected points from Q,R,S,T and W are noncollinear is

Answers

Answer:

2/5

Step-by-step explanation:

Probability is the likelihood or chance that an event will occur.

Probability = Expected outcome/Total outcome

Since we are to find the probability that 2 randomly selected points from Q,R,S,T and W are non-collinear

Non collinear points are points that doesn't lie on the same straight line. From the diagram given, the two point that are non colliear are (QR, QS, QT and QW making 4 2random non collinear points. Hence out expected number of outcome is 4.

For the total possible outcome, we are to find the number of ways we can randomly select two points from the 5 points given and this can be done using the combination rule.

This can therefore be done in 5C2 number of ways.

5C2 = 5!/(5-2)!2!

5C2 = 5!/3!2!

5C2 = 5*4*3*2*1/3*2*2

5C2 = 5*2

5C2 = 10 different ways

Hence the total possible outcome is 10

Therefore, the probability that 2 randomly selected points from Q,R,S,T and W are noncollinear will be 4/10 = 2/5

Estimate 2371 x1.84 divide 36.92

Answers

Answer:

Step-by-step explanation:

2371 x1.84 = 4362

4362 ÷ 36.92 = 118

the answer would be 118.1646804 but since the lowest sig fig in the question is 3 (1.84), we would have to round the answer to 3 SIG figs.

Final answer: 118

HELP ASAP
[tex]Given that $33^{-1} \equiv 77 \pmod{508}$, find $11^{-1} \pmod{508}$ as a residue modulo 508. (Give an answer between 0 and 507, inclusive.)[/tex]

Answers

Answer: 231

===================================================

Work Shown:

[tex]33^{-1} \equiv 77 \text{ (mod 508)}\\\\(3*11)^{-1} \equiv 77 \text{ (mod 508)}\\\\3^{-1}*11^{-1} \equiv 77 \text{ (mod 508)}\\\\3*3^{-1}*11^{-1} \equiv 3*77 \text{ (mod 508)}\\\\11^{-1} \equiv 231 \text{ (mod 508)}\\\\[/tex]

Notice how 33*77 = 2541 and 11*231 = 2541

[tex]2541 \equiv 1 \text{ (mod 508)}[/tex] since 2541/508 has a remainder of 1.

So effectively [tex]33*77 \equiv 1 \text{ (mod 508)}[/tex] and [tex]11*231 \equiv 1 \text{ (mod 508)}[/tex]

Scale the numerator and the denominator down by a factor of 3 (divide) to write a fraction equivalent to \frac{3}{12}
12
3

.

Answers

Answer:

[tex]\frac{1}{4}[/tex]

Step-by-step explanation:

Given

[tex]\frac{3}{12}[/tex] ← divide numerator and denominator by 3

= [tex]\frac{1}{4}[/tex]

Find the value:
please help

Answers

Answer:

the answer is 44

Step-by-step explanation:

4*2=8

48-(32:8)

48-(4)

44

I really hope it helps:))))))))))

Answer:

C. 32

Step-by-step explanation:

Order of Operations: Multiplication/Division (left to right) comes before Addition/Subtraction (left to right).

48 - 32/4 x 2 (Division)

48 - 8 x 2 (Multiplication)

48 - 16 (Subtraction)

32

Which of the following expressions represents the distance between -3.9, and -4.7?

Answers

Answer:

[tex]d = \sqrt{(x2 - x1) {}^{2} + (y2 - y1) {}^{2} }[/tex]

Step-by-step explanation:

[tex]d = \sqrt{( - 4 + 3) {}^{2} + (7 - 9) {}^{2} } [/tex]

[tex]d = \sqrt{(1 + 4)} = \sqrt{5} [/tex]


Write f(x)=5 -(x – 4)2 in the form f(x)= ax+bx+c.

Answers

Answer:

[tex]f(x) = 5 - (x - 4)^2[/tex].

Step-by-step explanation:

[tex]f(x) = 5 - (x - 4)^2[/tex]

[tex]f(x) = 5 - (x-4)*(x-4)[/tex]

[tex]f(x) = 5 - (x^2 - 4x - 4x + 16)[/tex]

[tex]f(x) = 5 - (x^2 - 8x + 16)[/tex]

[tex]f(x) = 5 - x^2 + 8x - 16[/tex]

[tex]f(x) = -x^2 + 8x - 11[/tex].

Hope this helps!

The table below shows the results from a study that compared speed (in miles per hour) and average fuel economy (in miler per gallon) for cars. Find a quadratic model for the data.

0.008
y=13.472x
2
+0.746x−0.008

y
=
25.836
x
+
0.049
y=25.836x+0.049

y
=

.
008
x
2
+
0.746
x
+
13.472
y=−.008x
2
+0.746x+13.472

y
=
0.049
x
+
25.836
y=0.049x+25.836

Answers

Note that the  quadratic model for the data is  y = -0.008x² + 0.75x + 13.47.

How is this so  ?

Here are the steps on how to  find a quadratic model for the data.

Make a   scatter plot of the data. The points should form an inverted U-shape. This suggests a quadratic model.Use the quadratic regression feature on your graphing calculator to find an equation of the model.

Here is the output of the quadratic regression feature on my graphing calculator

y = -0.008x² + 0.75x + 13.47.

where  -

x is the speed in miles per hour

y is the fuel economy in miles per gallon.

Learn more about Quadratic equation at:

https://brainly.com/question/1214333

#SPJ1

can someone please help me I need the answer urgently please​

Answers

Answer:

Step-by-step explanation:

AB ≅ BC.  So, ΔABC is an isosceles triangle

Opposite angles of equal sides are equal.

∠BAC = ∠BCA = x°

In ΔABC,

∠ABC + ∠BAC + ∠BCA = 180  {Angle sum property of triangle}

 56 + x + x = 180

56 + 2x = 180

        2x = 180 - 56

         2x = 124

           x = 124/2

           x = 62°

∠BAC = ∠BCA =  62°

∠DCF = ∠BCA   {Vertically opposite angles}

∠DCF = 62°

CDEF is a parallelogram.

In parallelogram, opposite angles are congruent.

∠DEF = ∠DCF

∠DEF = 62°

In a parallelogram, sum of adjacent angles = 180

∠DEF + ∠CDE = 180

62 + ∠CDE = 180

       ∠CDE = 180 - 62

      ∠CDE = 118°

∠CFE = ∠CDE   {In parallelogram, opposite angles are congruent}

∠CFE  = 118°

Help me slove and direction pls ty :)

Answers

Answer:

see explanation

Step-by-step explanation:

Solving

4x + 8 = 20 ( subtract 8 from both sides )

4x = 12 ( divide both sides by 4 )

x = 3

Each pack contains 3 paintbrushes

Answer:

x=3

Step-by-step explanation:

since the equation to use has already been given,you just have to group the like terms and solve for x

4x+8=20

4x=20-8

4x=12

then divide both sides by 4 in order to remain with x on one side

4x/4=12/4

x=3

each pack contains 3 paint brushes.

I hope this helps

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