SOLUTION: If f(x) = 4x - 3, find the following: f(-1) If f(x)= 5x -1, find the following: f(a-2) I do not understand either of these problems either. please help me I am lost, so los

Algebra ->  Trigonometry-basics -> SOLUTION: If f(x) = 4x - 3, find the following: f(-1) If f(x)= 5x -1, find the following: f(a-2) I do not understand either of these problems either. please help me I am lost, so los      Log On


   

Question 100575: If f(x) = 4x - 3, find the following:
f(-1)
If f(x)= 5x -1, find the following:
f(a-2)
I do not understand either of these problems either. please help me I am lost, so lost with this stuff.
Thank you,
Zack
Answer by tutorcecilia(2152) About Me  (Show Source):
You can put this solution on YOUR website!
f(-1) = 4(-1) - 3 [substitute x=-1 and solve]
f(-1)=-4-3
f(-1)=-7
or y=-7
.
Check by plugging (y=-7) back into the original equation and solve}
f(x) = 4x - 3
-7= 4x - 3 [solve for the x-term]
-7+3=4x
-4=4x
-4x/4=4/14
x=-1 [checks out]
.

f(a-2)= 5(a-2) -1 [substitute (x = a-2) and solve]
f(a-2)= 5a-10-1
f(a-2)=5a-11
or
y=5a-11
.
check by plugging (y=5a-11) back into the equation and solve for the x-term]
5a-11= 5(a-2) -1
5a-11+1=5a-10
5a-10=5a-10
,