how to solve f of g: find (g X f)(5), f = -3x-1,g = -x+2

[warriorchick1506]

the question says (g X f) (5) I assumed this meant that you take the equations they give you for f and g which are f(x)= -3x-1 & g(x)= -x+2.
i multiplyed the two together and then put 5 in for all the x's in the answer. how am i supposed to solve it?
I got 63 as the overall answer and i got all points taken away and i don't know where i went wrong!

 

[galactus]

Re: how to solve f of g??

The answer is 48. That is probably why.

\(\displaystyle (-x+2)(-3x-1)=3x^{2}-5x-2\)

\(\displaystyle 3(5)^{2}-5(5)-2=48\)

 

[stapel]

the question says (g X f) (5)

Your subject line says "f of g", which is function composition. Your post says "(g X f)", by which I will guess that you mean "(g * f)" (since of course "x" is the variable). Which are you supposed to be doing?

i got all points taken away and i don't know where i went wrong!

Unfortunately, since you have not shown your work, we have no idea where you went wrong (if at all), either. Sorry!

Please reply with a corrected statement of the exercise and its instructions, along with a clear listing of your work and reasoning. Thank you!

Eliz.