The ages of rocks in an isolated area are known to be approximately normally distributed with a mean of 7 years and a standard deviation of 1.8 years. What percent of rocks are between 5.8 and 7.3 years old?

Answer:

The expression in factored form is (3x - 7)(3x + 7)

Step-by-step explanation:

Here in this question, we are interested in using the difference of two squares to factor the given expression.

Mathematically, supposed we have two squares a^2 and b^2, and we are told to factorize a^2-b^2.

By using the difference of two squares;

a^2-b^2 can thus be written as;

(a-b)(a + b)

Now, we can apply same approach to the problem at hand.

9x^2 - 49

kindly note that 9x^2 can be written as ((3x)^2 and 49 can be written as 7^2

So applying what we have said earlier about difference of two squares;

9x^2 - 49 will be ;

(3x-7)(3x + 7)

Answer:

The answer is (3x - 7) (3x +7)

Step-by-step explanation:

Answer:

x = -1.5

Step-by-step explanation:

16x - 5 = 18x -2

Subtract 16x from each side

16x-16x - 5 = 18x-16x -2

-5 = 2x-2

Add 2 to each side

-5+2 = 2x-2+2

-3 = 2x

Divide by 2

-3/2 = 2x/2

-3/2 =x

Answer:

-3/2

Step-by-step explanation:

To solve this problem, start by moving all of your x's on to one side, and all of your constants on to the other as such:

16x-5=18x-2

     +2       +2

16x-3=18x

-16x    -16x

-3=2x

-3/2 = x

P.S. please give me brainliest. Thank you! :)

Answer: Hello:

Slope - intercept form is y = mx + b.

Since -1/2 is your slope and 5 is your y - intercept, all you need to do is substitute those values into the equation:

y = -1/2 + 5

Hope this helps!

Answer: 19 yards

Step-by-step explanation: 9.5x2=19

Answer:

Option D, 13.2

Step-by-step explanation:

m = √{7×(18+7)}

= √(7×25)

= 5√7

= 13.2 (rounded to the nearest tenth)

Answer:

C) 81 degrees

Step-by-step explanation:

all quadrilateral's sum of interiror angles is 360 degrees

right angles are 90 degrees

call measure of angle C =y

360=90+90+99+y

180=99+y

y= 81

Answer:

45.94%

Step-by-step explanation:

Probability-Above 45.94%

Z =0.1  

x= 61

µ 60

σ 9.8

Answer:

[tex]2\sqrt{3}+3[/tex]

Step-by-step explanation:

[tex]$\frac{3}{2 \sqrt 3 - 3}$[/tex]

Rationalize the fraction.

[tex]$\frac{3}{2 \sqrt 3 - 3}\cdot \frac{2 \sqrt 3 + 3}{2 \sqrt 3 + 3} =\frac{6\sqrt{3}+9 }{12-9} =\frac{6\sqrt{3}+9 }{3} =2\sqrt{3}+3 $[/tex]

Note that I used the positive signal because we would have a difference of squares.

Answer:

0.000000047

Step-by-step explanation:

Answer:

A

$2.50

Step-by-step explanation:

b = cost of bracelet

n = cost of necklace

2b+3n = 15.50

4b+1n = 13.50

Multiply the first equation by -2

-4b -6n = -31

4b +n = 13.50

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

-5n = -17.50

Divide each side by -5

-5n/-5 = -17.5/-5

n = 3.50

Now we can find b

4b+n = 13.50

4b+3.50 = 13.50

4b+3.50-3.50 = 13.50 -3.50

4b = 10

Divide by 4

4b/4 = 10/4

b = 2.50

Answer:

8

Step-by-step explanation:

|6x| - |- 2y|

Let x = -3 and y = 5

|6*-3| - |- 2*5|

|-18| - |-10|

Taking the absolute values

18 - 10

8

Answer:

-a

-------

10-a

Step-by-step explanation:

a

----

a-10

Multiply the top and bottom by -1

-1*a

-------

-1(a-10)

-a

------

-a+10

Rewriting

-a

-------

10-a

Answer:

-a/(10-a)

Step-by-step explanation:

To get from a - 10 to 10 - a,  you just have to multiply by -1.

So fi you multiply both the top and bottom by -1, you'd get -a/(10-a).

Answer:

[tex](x+6)(x-6)[/tex]

Step-by-step explanation:

Hi there!

The difference of squares theorem states that [tex]a^2-b^2=(a+b)(a-b)[/tex].

We're given:

[tex]x^2-36[/tex]

This can be rewritten since 36 is a perfect square:

[tex]=x^2-6^2[/tex]

Use the difference of squares theorem:

[tex]=(x+6)(x-6)[/tex]

I hope this helps!

Answer:

(x-6)(x+6)

Step-by-step explanation:

x^2 -36

Rewriting

x^2 - 6^2

We know a^2 - b^2 = (a-b)(a+b)

(x-6)(x+6)

Answer:

6x - 4

Step-by-step explanation:

4 less than 6 times x

6x - 4

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-Chetan K

Answer:

The error she made was that she was adding x and 2.75. She should subtract 2.75 from x.

Another mistake that she made was that she sold each for $7 assuming that she would make a profit of 78, but she should see each necklace for $12.5 so that she could make a profit of $78.

Step-by-step explanation:

The error she made was that she was adding x and 2.75.

She should write the equation as 8 (x - 2.75) = 78; as she spends $2.75 to make a necklace.

By using the correct equation: 8 (x - 2.75) = 78

=> 8x - 22 = 78

=> 8x = 78 + 22

=> 8x = 100

=> x = 100/8

=> x = 12.5

Another mistake that she made was that she sold each for $7 assuming that she would make a profit of 78, but she should see each necklace for $12.5 so that she could make a profit of $78.

Hope this helps you.

Answer:

C

Step-by-step explanation: Nice

Answer:

A) The percentage is given by (The new value)/(The old value)*100 = 120%

B) The increase in value is $90000

C) The increase as a percentage is (90000/450000)*100=20%

a. The new value is 120% of the old value.

b. The increase in value over the three-year period is $90 000.

c. The increase in value over the three-year period is 20% of the original value.

The percentage is defined as a ratio expressed as a fraction of 100.

a. To find the new value as a percentage of the old value, we can divide the new value by the old value and multiply by 100 to get a percentage:

New value as a percentage of old value = (New value / Old value) x 100%

= ($540 000 / $450 000) x 100%

= 120%

Therefore, the new value is 120% of the old value.

b. To find the increase in value over the three-year period, we can subtract the old value from the new value:

Increase in value = New value - Old value

= $540 000 - $450 000

= $90 000

Therefore, the increase in value over the three-year period is $90 000.

c. To find the increase in value as a percentage of the original value, we can divide the increase in value by the old value and multiply by 100 to get a percentage:

Increase in value as a percentage of original value = (Increase in value / Old value) x 100%

= ($90 000 / $450 000) x 100%

= 20%

Therefore, the increase in value over the three-year period is 20% of the original value.

Learn more about the percentages here:

brainly.com/question/24159063

#SPJ2

Answer:

x = 4, x = -4

Step-by-step explanation:

Step-by-step explanation:

Move terms to the left side

2=16

x^{2}=16x2=16

2−16=0

Use the quadratic formula

Simplify

Evaluate the exponent

Multiply the numbers

Add the numbers

Evaluate the square root

Multiply the numbers

=0±82

2

Separate the equations

To solve for the unknown variable, separate into two equations: one with a plus and the other with a minus.

=0+82

x= 0 + 8 over 2

=0−82 over 2

Rearrange and isolate the variable to find each solution

=4

x=4x=4

ans =−4

Answer:

JKM is acute and MKL is obtuse

Step-by-step explanation:

because an acute triangle's interior angles are always 180° and an obtuse triangle's sum is greater than 90°

Answer:

20,160 pounds

Step-by-step explanation:

bricks in each row * number of rows * pound of each brick

Answer:

20160 lbs

Step-by-step explanation:

To find the amount of bricks, multiply 36 by 140 which equals 5040. Then, multiply 5040 by the weight: 4. 5040×4=20160

Answer:

[tex]\huge\boxed{x = -\frac{5}{6}}[/tex]

Step-by-step explanation:

[tex]f(x) = -12x+7[/tex]

Given that f(x) = 17

[tex]17 = -12x+7[/tex]

Subtracting 7 to both sides

[tex]17-7 = -12x[/tex]

10 =  -12 x

Dividing both sides by 12

[tex]x = - \frac{10}{12}[/tex]

[tex]x = -\frac{5}{6}[/tex]

Answer:

-5/6 =x

Step-by-step explanation:

f(x) = -12x+7

We want to find x when f(x) = 17

17 = -12x+7

Subtract 7 from each side

17-7 = -12x +7-7

10 = -12x

Divide each side by 12

10/-12 = -12x/-12

-5/6 =x

Answer:

the total amount (balance) after x years with a principal of $19 and with simple interest of 1.3% is given by:

balance(x) = 19(1+0.013x)

Calculate for two values of x (for example x=0, balance = 19(1+0)=$19

and choose the graph that fits both points.

Step-by-step explanation:

Answer:

B. 6 miles per practice

Step-by-step explanation:

12 miles over the course of 2 track practices divided by 2  

12/2 = 6

6 miles per one track practice

Answer:

The four legged stool is the one that rocks slightly from side to side. The three legged stool does not.

Step-by-step explanation:

The four legged stool is the one that rocks slightly because the three legs determine a plane, and the three legs are stuck on that single plane.

Answer:

After 6 years = 87120 people.

Before 6 years = 5808 people.

Step-by-step explanation:

To calculate how many populations that are added in every 10% in 3 years:

72600 × 10/100 = 7260

After 6 years = 72600 + 7260 × 2 = 87120 people.

Before 6 years = 72600 - 7260 × 2 = 5808 people.

Answer:  Choice A)  -3

Work Shown:

[tex]\log_{2}(x+7) = 2\\\\x+7 = 2^2\\\\x+7 = 4\\\\x = 4-7\\\\x = -3\\\\[/tex]

Which leads us to choice A. In the second step, I used the rule that [tex]\log_b(y) = x[/tex] is equivalent to [tex]y = b^x[/tex]. For each equation, the b is the base. Note how logs undo exponents and vice versa.

Answer:

-3

Step-by-step explanation:

log2(x+7) = 2​

Raise each side by base 2

2^log2(x+7) = 2^2​

x+7 = 4

Subtract 7 from each side

x+7-7 = 4-7

x=-3

Answer:

Step-by-step explanation:

First of all AD is 9 units long. Anything less than or equal to 9 is not an answer because the scale factor is greater than 1. That means that anything over 9 will work.

So the answer must be 12 or 15 from those answers given.

Answer:

Answer

Step-by-step explanation:

The answer is 12 AND 15

D and E