## Skittles456 2 years ago Help http://prntscr.com/12brlc

1. timo86m

take derivitive first :D

2. timo86m

brb :)

3. Skittles456

okay tell me when your back

4. goformit100

First of all for solving this question do you know the conception of : Derivatives. and i know you can then definitely can solve the question on your own

5. timo86m

take dervitive first of all : can you do that?

6. Skittles456

7. timo86m

8. Skittles456

A little. I remember seeing it. Didnt go into much detail

9. timo86m

you weren't paying much attention lol :P

10. Skittles456

Can you tell me. or send me a link about them. either one is fine. :)

11. timo86m

anyhoo first we must take the derivative aka differential. x^2+5*x luckily this one is one of the most basic and using the rules aka formulas. http://myhandbook.info/form_diff.html look at constant rule, sum rule and power rule :D try it out if you can

12. timo86m

also the factor rule :)

13. Skittles456

which factor rul

14. Skittles456

what do i plug in for d?

15. timo86m

and d/dx just means the derivative operator so d/dx(x^2+5*x) means derivitve of x^2+5*x with respect to x d/dx(x^2)+ d/dx(5*x) the sum rule this makes it more easy :) seperated into 2 small derivatives instead of one big one. we handle it as 2 seperate problems d/dx(x^2)= 2x by the power rule simply decrease the exponent by 1 and multiply the variable and coefficient by the exponent you just decrased. you get 2 :). d/dx(5*x) = 5 by factor rule now you plug back in because you did them seperately 2x+5 and that is derivative :) with me so far?

16. Skittles456

yes

17. timo86m

2x+5 is also a tangent function which gives the slope of the tangent at any given x. For example at x=0 the slope is 5. they want it at 4 tho. So plug it in 2(4)+5=8+5=13 That is your answer :)

18. Skittles456

no

19. Skittles456

But i saw where I messed up!

20. Skittles456

its fixed

21. timo86m

was i right tho :)

22. Skittles456

Thank you so much!

23. timo86m

weird tho if you not familiar with calc 1 concepts then it is weird problem to do.

24. Skittles456

Im not in Calc 1 lol

25. timo86m

precalc?

26. Skittles456

yes

27. bahrom7893

hmm maybe if we do: x1 = 3 x2 = 5 y1 = 9+15 = 24 y2 = 25+25 = 50 M = (y2-y1)/(x2-x1) = (50-24)/(5-3) = 26/2=13

28. bahrom7893

Voila, the answer given to us by calculus matches up: f'(4) = 2x+5 = 2*4+5=13

29. timo86m

aaa :) calc way is easier tho.

30. bahrom7893

:)

31. Skittles456

Thank you both!

32. Skittles456

Im going through all the qustions I missed so i can understand them better

33. timo86m

good for you :D