Question

I dont understand how to do this its factoring quadratics

Answer 1

olume = length * height * width  

Therefore 280 = 4 * (n + 2) * (n + 5)  

Divide both sides of the equation by 4  

70 = (n + 2)(n +5)  

Expand  

70 = n^2 + 5n + 2n + 10  

Subtract 70 from both sides and simplify  

0 = n^2 + 7n -60  

Factor  

(n +12)(n -5) = 0  

Therefore n = -12 or + 5  

As n cannot be less than -2 as you cannot have a negative dimension, it means that n = 5 and the sides are 4, (5 + 2), (5 + 5) = 4, 7 and 10 inches respectively  

Volume is therefore  

4*7*10 = 280 = correct  

Hope this helped!