Question

Help me, please? thanks!

Answer 1

a = 9 or a = 1/3

f(x)=3x^2-28x

f(a)=3x^2-28x

-9=3x^2-28x

3x^2-28x+9=0

by factory,

(3x-1)(x-9)=0

3x=1 or x=9

x=1/3 or x=9

x=a