Question

A box has a total surface area of 100. The length of the box is equal to twice its width, as well as equal to 3 less than its height. What is the height of the box?

Answer 1

I think it’s 7 sorry if it’s wrong Chile :)

Answer 2

h=7

Explanation:

First we need to define the formula for surface area

2(wl+hl+hw)=100

Now we can replace length with x

That makes width .5x and height x+3

2(.5x^2+x^2+3x+.5x^2+1.5x)=100

2(2x^2+4.5x)=100

2x^2+4.5x=50

2x^2+4.5x-50=0

Insert into quadratic equation (a=2x^2, b=4.5, c=-50)

x=4 or -6.25

x can't be negative so x is 4

h=x+3=7

h=7