Find f(-x) for a function

Find f(-x) for function:

f(x)= 6x^2 + 3x - 5

f(-x)= ?

substitute x with -x
f(-x)=6x^2 - 3x - 5

just put (-x) instead of (x) value

your function will be

f(-x)=6(-x)^2+3(-x)-5

which is same as

f(-x)=6x^2-3x-5

f(-x) = 6(-x)^2 + 3(-x) - 5
f(-x) = 6x^2 - 3(x) - 5