Question

Question 1

Solve the equation that models the volume of the shipping box, 8(n + 2)(n + 4) = 1,144. If
you get two solutions, are they both reasonable?​

Answer 1

Simplify the equation, and set it equal to zero to prepare for factoring.

Multiply the two factors in parentheses using the distributive property:

8(n2 + 2n + 4n + 8) = 1,144

Combine like terms inside the parentheses:

8(n2 + 6n + 8) = 1,144

Multiply the terms inside the parentheses by 8 using the distributive property:

8n2 + 48n + 64 = 1,144

Set the equation equal to zero by subtracting 1,144 from each side:

8n2 + 48n − 1,080 = 0

Factor out the GCF, which is 8:

8n2 + 48n − 1,080 = 0

8(n2 + 6n − 135) = 0

Divide both sides of the equation by 8:

n2 + 6n − 135 = 0

Compare the equation with the standard form ax2 + bx + c = 0, and get a, b, and c:

a = 1, b = 6, c = -135

The leading coefficient of the equation is 1. So, find two numbers that have a sum of 6 and a product of -135:

6 = -9 + 15

-135 = -9 • 15

The two numbers are -9 and 15. Use the two numbers to write the factors of the quadratic expression:

(n − 9)(n + 15) = 0

Use the zero product property, and solve for n:

n − 9 = 0 or n + 15 = 0

n = 9 or n = -15

There are two solutions for n. But since n represents the width of the helmet box, it can’t be negative. Therefore, the only reasonable solution is n = 9

Answer 2

n = -15 and n = 9. n = -15 is not reasonable because you can't have negative boxes or negative units of measurement.

Explanation:

8(n + 2)(n + 4) = 1,144

(n + 2)(n + 4) = 143

n^2 + 2n + 4n + 8 = 143

n^2 + 6n - 135 = 0

(n + 15)(n - 9) = 0

n + 15 = 0

n = -15

n - 9 = 0

n = 9

I got two solutions: n = -15 and n = 9. Only one is reasonable because you cannot have a negative number of boxes or negative weight.

Hope this helps!