SOLUTION: 17. f(x) = 15x3 + 13x2 - 15x + 15 g(x) = 15x + 11 find g(f(9)) A. 639 B. -5943226 C. -52466 D. -6288203 E. 178031 F. -4595 18. f(x) = -13x2 - 13x + 14

Algebra ->  Functions -> SOLUTION: 17. f(x) = 15x3 + 13x2 - 15x + 15 g(x) = 15x + 11 find g(f(9)) A. 639 B. -5943226 C. -52466 D. -6288203 E. 178031 F. -4595 18. f(x) = -13x2 - 13x + 14       Log On


   

Question 1197810: 17. f(x) = 15x3 + 13x2 - 15x + 15
g(x) = 15x + 11
find g(f(9))
A. 639
B. -5943226
C. -52466
D. -6288203
E. 178031
F. -4595

18. f(x) = -13x2 - 13x + 14
g(x) = -13x - 11
find g(g(3))
A. 639
B. 178031
C. -5943226
D. -52466
E. -6288203
F. 752
Found 2 solutions by ikleyn, MathLover1:
Answer by ikleyn(52794) About Me  (Show Source):
You can put this solution on YOUR website!
.

(17) It is a two-steps problem.

Solve it in two steps.

As the first step, calculate f(9).

As the second step, substitute the value f(9) into the formula for g(x) instead of x and calculate the answer.


(19) It is a two-steps problem.

Solve it in two steps.

As the first step, calculate g(3).

As the second step, substitute the value g(3) into the formula for g(x) AGAIN instead of x and calculate the answer.

Notice that you don't need the formula for f(x) in this problem.



Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
17.
f%28x%29+=+15x%5E3+%2B+13x%5E2+-+15x+%2B+15
g%28x%29+=+15x+%2B+11


find g%28f%289%29%29

first find g%28f%28x%29%29
g%28f%28x%29%29=g%2815x%5E3+%2B+13x%5E2+-+15x+%2B+15%29
g%28f%28x%29%29=15%2815x%5E3+%2B+13x%5E2+-+15x+%2B+15%29%2B11
g%28f%28x%29%29=225+x%5E3+%2B+195+x%5E2+-+225+x+%2B+236


then
g%28f%289%29%29=225+%2A9%5E3+%2B+195%2A9%5E2+-+225%2A9+%2B+236
g%28f%289%29%29=178031

answer: E.+178031


18.
f%28x%29+=+-13x%5E2+-+13x+%2B+14
g%28x%29+=+-13x+-+11
find g%28g%283%29%29
g%28g%28x%29%29=g%28+-13x+-+11%29
g%28g%28x%29%29=-13%28+-13x+-+11%29-11
g%28g%28x%29%29=169+x+%2B+132
then
g%28g%283%29%29=169+%2A3+%2B+132
g%28g%283%29%29=639
answer:
A. 639