tmagloire1 one year ago ap calc ab help http://prntscr.com/8grqwg

1. tmagloire1

@misty1212

2. anonymous

$\frac{d}{dx}(g(f(x))) = g'(f(x)) \cdot f'(x)$

3. misty1212

HI!!

4. misty1212

and hi @Jhannybean !!

5. anonymous

Hi!!! @misty1212

6. tmagloire1

Hi everyone xD Thanks for helping me!!

7. misty1212

you have all the numbers you need to plug in to what @Jhannybean wrote above plug them in, see what you get

8. tmagloire1

Wait so I understand how to plug in the f(x) and f'(x) but how do I do the g(x) and g'(x)

9. misty1212

let me just add one little bit $\frac{d}{dx}(g(f(3x))) = g'(f(3x)) \cdot f'(3x)\cdot 3$

10. anonymous

So now we have $$g'(f(x)) \cdot f'(x)$$ take it one step at a time. $g'(f(1)) \cdot f'(1)=~?$

11. misty1212

careful a little it is $$f(3x)$$ so at $$x=1$$ it is $$f(3)$$

12. anonymous

Oooo stupid me. I misread a portion of the problem.

13. anonymous

Yeah. Just noticed.

14. tmagloire1

So if x=1 at f(3x) = f(3) what am i supposed to use to plug in.. im actually really confused

15. misty1212

now got to read them off of the table at $$x=1$$ it is $g'(f(3)) \cdot f'(3)\cdot 3$

16. misty1212

what is $$f'(3)$$ from the table?

17. tmagloire1

2

18. tmagloire1

i mean 10

19. anonymous

and what is $$f(3)$$ from the table?

20. tmagloire1

2

21. misty1212

and finally, what is $$g'(2)$$?

22. tmagloire1

5

23. tmagloire1

So would it be 5(10)(3)=150?

24. anonymous

Yeah

25. misty1212

number therapy for learning the chain rule

26. tmagloire1

Haha thank you so much! Okay so would that be how you do it at x=1 or is that just an example from the chart?

27. anonymous

We did it at x=1

28. tmagloire1

Oh okay i understand so we just broke it up into components

29. tmagloire1

Thank you so much both of you for your help!!

30. anonymous

$g'(f(1))\cdot f'(1) = \\ g'(f(3(1))) \cdot f'(3(1)) \cdot 3 = \\ g'(f(3)) \cdot f'(3) \cdot 3 = \\ g'(2) \cdot 10\cdot 3 = \\ 5 \cdot 10\cdot 3 = 150$