How do you solve (2s-1)^{2}=225?

2 Answers
Jun 18, 2017

x=-7 or x=8

Explanation:

There is a rule that states (a+b)^2=a^2+2ab+b^2

In this case, a is 2s and b is -1.

Therefore

4s^2-4s+1=225

Subtract 225 from both sides.

4s^2-4s-224=0

Divide by 4.

s^2-s-56=0

You can factorise this as follows :

(x+7)(x-8)

Set each factor equal to 0.

x+7=0
x=-7

x-8=0
x=8

Jun 18, 2017

s = 8 or s = -7

Explanation:

Although this equation leads to a quadratic trinomial, it is in the form x^2 =c" " so we can just find the square root of both sides,

(2s-1)^2 = 225

2s-1 = +-sqrt225

2s = +-sqrt225+1

s = (+15+1)/2 = 8

s = (-15+1)/2 = -7