## Barrelracing one year ago Given that f(x) = 2x + 1 and g(x) = −5x + 2, solve for f(g(x)) when x = 3. A) -91 b) -33 c) -25 d) 35

1. Michele_Laino

hint, by definition of compiste function, we can write this: $\Large f\left( {g\left( x \right)} \right) = 2g\left( x \right) + 1 = 2\left( { - 5x + 2} \right) + 1 = ...?$

2. Michele_Laino

3. Barrelracing

do I have to plug something in or just solve?

4. Michele_Laino

solve as an algebraic expression

5. Michele_Laino

hint: $\Large 2\left( { - 5x + 2} \right) + 1 = - 10x + 4 + 1 = ...?$

6. Barrelracing

it all cancels out. -10x + 4 + 1 = -10x + 4 + 1

7. Michele_Laino

now simplify further, what do you get?

8. Michele_Laino

4+1=...?

9. Barrelracing

5!!! :)

10. Michele_Laino

ok! so we got this: $\Large f\left( {g\left( x \right)} \right) = - 10x + 5$

11. Michele_Laino

please substitute x=3 at the right side, what do you get?

12. Barrelracing

f(g(x)) = -25

13. Michele_Laino

that's right!

14. Michele_Laino

$f\left( {g\left( 3 \right)} \right) = - 25$

15. Barrelracing

thank you so much for your help

16. Michele_Laino

:)