Consider the functions f(x) = 3x2 and g(x) = −2x − 5. What is the value of f[g(−4)]?

9

−31

27

3

Question

Consider the functions f(x) = 3x2 and g(x) = −2x − 5. What is the value of f[g(−4)]?

9

−31

27

3

anonymous · Answer

This is asking you to compose the functions, so begin with the g function and substitute -4 in for x to get an answer.  Take this answer and substitute it into x in the f function.

anonymous · Answer

Nope, you try it.  I'll tell you if you're correct or not.

anonymous · Answer

ok, first try to find g(-4)

you know that g(x) = −2x − 5

now just instead of x plug in -4

g(-4) = -2(-4) -5 = ?

solve the equation to find ?

anonymous · Answer

3

anonymous · Answer

Good.  Now put 3 in for x in the f function.

anonymous · Answer

I solved it and got -31. Is that correct?

anonymous · Answer

Isn't f(x) = 3x^2????
Try again.

anonymous · Answer

f(x) = 3*x^2

f(3) = 3*(3^2) = ?

solve for ?

anonymous · Answer

27

anonymous · Answer

Nicely done.

anonymous · Answer

So is that the answer?

anonymous · Answer

yes.

anonymous · Answer

Can u help me with 2 more problems like this?

anonymous · Answer

ok

anonymous · Answer

f(x) = 8x + 2 and g(x) = 5x - 3. What is the value of f/g (4)?