Question

Use
f(x) = 5x − 4
and
g(x) = 3 − x^2
to evaluate the expression.
(g compose f)(x)

Answer 1

(g o f )(x) means g(f(x)), the output of f(x) will be the input of g(x)

so for the x value of g(x), substitute the function f(x).

Answer 2

Okay, I don't even know what I'm doing wrong but I'm not coming out to the correct answer according to webassign. I watched their 'watch it' video multiple times and that is not helping me either.

'Watch it' video: Use f(x)=3x-5 and g(x)=2-x^2 to evaluate the expression.
(b) (g compose f)(x)=g(f(x))
=g(3x-5)
=2-(3x-5)^2
=2-[9x^2-30x+25]
=-9x^2+30x-23

I don't even know where they got the 30 from and that is throwing me off.

Answer 3

\((a-b)^2 = a^2 - 2ab + b^2\)

Answer 4

I seriously do not know what I'm doing wrong. But thanks anyways.

Answer 5

from the video:
(g compose f)(x)=g(f(x))
=g(3x-5)
=2-(3x-5)^2-> substitute f(x) into g(x)
=2-[9x^2-30x+25] -> expand the exponent
=-9x^2+30x-23 -> simplify

From your problem:
3-(5x-4)^2 -> substitute f(x) into g(x)
3-(25x^2-40x+16) -> expand the exponent
3-25x^2+40x-16 -> simplify
-25x^2+40x-13

which part you didn't get??