Question

I think of a number, add 5,then square the answer. The result is 100. What could the number be?

x=
x=

Answer 1

x= 5 or -15

Step-by-step explanation:

let the number be x

(x+5)^2=100

x^2+10x+25=100

x^2+10x-75=9

look for factors of 75 that when you gives you 10 and when you multiply gives you -75

those factors are 15 and -5

replace 10x with 15x and -5x

x^2+15x-5x-75=0

then group them, and factorize

x(x+15)-5(x+15)=0

x-5=0 or x+15=0

x= 5 or x= -15

Answer 2

x = 5

x = -15

Step-by-step explanation:

Let the number be "x"

===================

• (x + 5)² = 100

• x + 5 = ±√100

• x + 5 = ±10

• x + 5 = 10, x + 5 = -10

• x = 10 - 5, x = -10 -5

• x = 5, -15