SOLUTION: can you help me with problem? it is from a multiple choice hand out. f is a function defined by f(x)= -x/5 and g is a funciton defined by g(x)= 7-3x then 4g-5f= thanks for

Algebra ->  Functions -> SOLUTION: can you help me with problem? it is from a multiple choice hand out. f is a function defined by f(x)= -x/5 and g is a funciton defined by g(x)= 7-3x then 4g-5f= thanks for      Log On


   

Question 74313: can you help me with problem? it is from a multiple choice hand out.
f is a function defined by f(x)= -x/5 and
g is a funciton defined by g(x)= 7-3x then
4g-5f=
thanks for any help
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
When you say 4g you're saying 4*g(x) which means that you're going to multiply 4 by the output g(x). So if I plug in x=0 for g(x) I get
g%280%29=+7-3%280%29
g%280%29=7
So 4*g(0)=4(7)=28.
Now we're going to do this in terms of x
4g%28x%29-5f%28x%29=4%287-3x%29-5%28-x%2F5%29
4g%28x%29-5f%28x%29=28-12x%2B%285x%2F5%29
4g%28x%29-5f%28x%29=28-12x%2Bx
4g%28x%29-5f%28x%29=28-11x
So 4 times g(x) plus 5 times f(x) is 28 minus 11x. I hope this makes sense.