Given the quadratic function f(x) = x^2 - 12x + 36 how do you find a value of x such that f(x) = 25?

1 Answer
Jun 20, 2016

:. x=11, x=1.

Explanation:

f(x)=25
:. x^2-12x+36=25.
:. x^2-12x+36-25=0.
:. x^2-12x+11=0.
:. x^2-11x-1x+11=0.......... [11xx1=11,11+1=12]
:. x(x-11)-1(x-11)=0.
:. (x-11)(x-1)=0.
:. x=11, x=1.

Alternatively, we see that f(x)=(x-6)^2.
Hence, f(x)=25
rArr (x-6)^2=25=5^2.
rArr (x-6)=+-5
rArr x=6+-5
rArr x=11, or, x=1, as before!