Question

The difference of the square of a number and 36 is equal to 5 times that number. Find the positive solution.

Answer 1

x=-4, x=9

Explanation:

We write this into words:

difference = subtraction

square = ^2

a number = x

is equal to = =

5 times that number = 5x

x^2-36 = 5x

write in standard form

x^2-5x-36

what adds to -5 and multiplies to -36?

-9 and 4!

(x-9)(x+4)

x-9 = 0

x= 9

x+4 = 0

x=-4

Answer 2

9

Explanation:

Let the number = x.

x² - 36 = 5x

x² - 5x - 36 = 0

(x - 9)(x + 4) =0

x = 9 or x = -4

Answer: 9