SOLUTION: Hi there, I really need some help on this problem. I have some of it worked out, but I'm confused on the second part: Let f (x) = 2x2 + 8x – 5 and g(x) = 4x – 1 (a) Find

Algebra ->  Logarithm Solvers, Trainers and Word Problems -> SOLUTION: Hi there, I really need some help on this problem. I have some of it worked out, but I'm confused on the second part: Let f (x) = 2x2 + 8x – 5 and g(x) = 4x – 1 (a) Find       Log On


   

Question 1039986: Hi there, I really need some help on this problem. I have some of it worked out, but I'm confused on the second part:
Let f (x) = 2x2 + 8x – 5 and g(x) = 4x – 1
(a) Find the composite function (f o g)(x) and simplify the results. Show work.
5

(b) Find (f o g)(-1) . Show work.
I'm not sure what I need to do on part b, any help is greatly appreciated!
Found 2 solutions by josgarithmetic, stanbon:
Answer by josgarithmetic(39616) About Me  (Show Source):
You can put this solution on YOUR website!
Evaluate the composition for x=-1.

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Let f (x) = 2x^2 + 8x – 5 and g(x) = 4x – 1
(a) Find the composite function (f o g)(x) and simplify the results. Show work.
fog(x) = f[g(x)] = f[4x-1] = 2(4x-1)^2+8(4x-1)-5
= 2(16x^2 -8x+1)+32x-8-5
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= 32x^2 - 16x + 2 + 32x - 13
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= 32x^2 + 16x - 11
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(b) Find (f o g)(-1) = f[g(-1] = f[-4-1] = f[-5]
= 2(-5)^2 + 8(-5) -5
= 50 - 45
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= 5
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Cheers,
Stan H.
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