SOLUTION: Hi! I'm stuck on this problem and I'm not sure how to go about it. Can anybody please help me solve this? Suppose ​f(x) = x^2 - 5x + c and ​g(x) = f(x)/4 - 4. Find

Algebra ->  Functions -> SOLUTION: Hi! I'm stuck on this problem and I'm not sure how to go about it. Can anybody please help me solve this? Suppose ​f(x) = x^2 - 5x + c and ​g(x) = f(x)/4 - 4. Find       Log On


   

Question 1181760: Hi!
I'm stuck on this problem and I'm not sure how to go about it.
Can anybody please help me solve this?
Suppose ​f(x) = x^2 - 5x + c and ​g(x) = f(x)/4 - 4.
Find ​f(2​) if ​g(​-1) = 1
Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!
Suppose f%28x%29=x%5E2-5x%2Bc and ​g%28x%29+=+f%28x%29%2F4+-4.
Find
f%282%29 if g%28-1%29=1

if ​g%28-1%29=1, then

1=+f%28-1%29%2F4-4
f%28-1%29=5%2A4
f%28-1%29=20

then use it to calculate c
f%28x%29=x%5E2-5x%2Bc
20=%28-1%29%5E2-5%28-1%29%2Bc
​20+=1+%2B+5+%2B+c
c=14

your functions f%28x%29 and g%28x%29 are
​f%28x%29+=+x%5E2+-+5x+%2B14
and
g%28x%29+=+%28x%5E2+-+5x+%2B14%29%2F4+-+4
g%28x%29+=x%5E2%2F4+-+%285x%29%2F4+-+1%2F2

and finally we can calculate f%282%29+:

​f%282%29+=+2%5E2+-+5%2A2+%2B14
​f%282%29+=+4+-+10+%2B14
f%282%29+=++-+6+%2B14
​f%282%29+=+8