## anonymous 5 years ago --->>>Problem #8

1. anonymous

2. anonymous

Why is the answer not 14?

3. anonymous

i did 142-2/10-0 = 140/10 = 14

4. EarthCitizen

$f(t)=t ^{2}+4t+2 \therefore f(t)\prime=2t+4$

5. anonymous

???

6. EarthCitizen

you differentiate f(t)

7. anonymous

o wait

8. anonymous

i plugged in 10 but i wasnt supposed to, right?

9. EarthCitizen

yep

10. anonymous

just 0 and t

11. EarthCitizen

no, find the zeroes of the first function f(t) leaving you with $t=-2-\sqrt(2) , \sqrt(2)-2$

12. anonymous

im kinda confused

13. anonymous

14. EarthCitizen

$2t+4=10 \therefore t=3$ i think

15. anonymous

im getting even more confused... i dont think we've covered what you are doing in my class yet

16. EarthCitizen

have you done differentiation ?

17. anonymous

dont think so? if we have, i must've been day dreaming or something

18. EarthCitizen

ouch! not a good thing to solve calculus if you haven't done it before you'll just be hurting your mind

19. anonymous

20. EarthCitizen

yh, what was it ?

21. anonymous

idk yet, you tell me lol

22. EarthCitizen

what are the options then ?

23. anonymous

no options

24. anonymous

it just tells you if you got it right or wrong

25. EarthCitizen

shoot!

26. anonymous

at least i get unlimited tries lol

27. EarthCitizen

since y=mx+c then f(t)'=2t+4

28. anonymous

its 6

29. anonymous

30. anonymous

i do just plug in 0 and t and then do rate of change

31. EarthCitizen

alryt, show me wh@ you did ?

32. EarthCitizen

we are all learning

33. anonymous

f(0)^2+4(0)+2=2 f(t)=t^2+4t+2 t^2+4t+2-(2)/t =t+4 t=6 because 6+4 is 10 (10 is given in the problem)

34. EarthCitizen

alryt, i see. why did you divide thru by t ?

35. anonymous

its usually by h but since there is no h i made it a t (im using the difference quotient formula or whatever its called)

36. EarthCitizen

alryt, so you haven't done calculus before ?

37. anonymous

first time

38. EarthCitizen

awesome!

39. anonymous

why is that? lol

40. EarthCitizen

yh, coz you haven't done calculus yet and you did a calculus problem, so th@s awesome

41. anonymous

lol

42. anonymous

i posted another question that you could maybe help me with

43. EarthCitizen

alryt, i'll try wish me luck