Question

Hi, how did they get -500? And what do I do for the A part because i know it’s not to solve it since that’s what you do in B so I’m a bit confused please help. Thank you

Answer 1

Explainations to part A is written below.

Part B : x = 25 is the solution as length cannot be negative.

Explanation:

Hey there, it's pretty simple!

The formula for the volume of a cube is

Volume = Length × Width × Height.

Let's assume length = x, height = 2x - 30, and width as 10

also note that volume is 5000, plugging this into the equation, we get

(x)(10)(2x - 30) = 5000

10x (2x-30) = 5000

x(2x-30) = 500

(this is how they got 500 and hence the -500 when we shift this to another side to create a quadratic equation).

2x^2 - 30x = 500

2x^2 - 30x - 500 = 0

Part b)

Factoring 2(x^2 - 15x - 250) = 0, we get

2 (−25) (+10)

tadah!