The are of a rectangle is 40 square centimeters. Find the value of x

Question

40 square centimeters

Width of x+6

What is x

Answer 1

[I am assuming that x is the chosen variable for Length in this problem]

Remember that for a rectangle, Area = (Length)(Width) or A = LW

It is given that W = x + 6 , A = 40, L = x

We can make an equation with one unknown by substituting in the following way

A = LW

40 = x(x + 6)

40 = x^2 + 6x

Move everything to one side, and solve for x,

x^2 + 6x - 40 = 0

(x - 4)(x + 10) = 0

So, x = 4 or x = -10.

We know that x cannot be -10 because a side length cannot be negative. Therefore, x = 4.