## anonymous 4 years ago Can someone help me solve this calc problem? It's attached.

1. anonymous

2. anonymous

Sample problem:

3. anonymous

you have the solution with the explanation, so what else do you need?

4. anonymous

I have a sample problem. I've tried applying the steps to the actual problem but it's confusing.

5. anonymous

So instead of substituting 6 and 1 into the v's, you'll substitute 5 and 2.

6. anonymous

The substitution takes place at the part where the expression is in square brackets. [ ]

7. anonymous

You'll plug in 5 first and evaluate. Keep that answer on the side somewhere. Then you'll go back to the square brackets again, plug in 2 and evaluate. Whatever you get as the answer, you'll subtract that from the answer you got when you plugged in 5.

8. anonymous

Can you wait while I do it, and tell me if it's correct?

9. anonymous

Yes.

10. anonymous

I got 77.5 when I plugged in 5.

11. anonymous

I got -7.5

12. anonymous

There's an extra negative sign next to the red negative sign. Ignore the extra one.

13. anonymous

${-3(5)^{2}\over 2}+6(5)$

14. anonymous

Okay, so if I plug in 1, I'll get -3/2+8 = 6.5

15. anonymous

No. 4.5.

16. anonymous

Look at the equation I wrote above.

17. anonymous

What do you get when you evaluate that expression?

18. anonymous

Oh, I forgot to square it.

19. anonymous

Then I get: (-7.5+4.5) - (-3/2 +8) = -9.5 or -19/2.

20. anonymous

It's cool.

21. anonymous

It's not correct though.

22. anonymous

You're doing more than what it's asking for. The only values you're evaluating are 5 and 2. Not 6 and 1.

23. anonymous

6 and 1 are solely used in the example.

24. anonymous

You never answered my question. What do you get when you evaluate the expression I wrote above?

25. anonymous

-7.5

26. anonymous

Awesome. Now imagine the 5 is gone and a 2 is in its place in the expression above. What do you get now?

27. anonymous

Replace BOTH 5s with 2s. Not just the one on the left.

28. anonymous

6

29. anonymous

Perfect. Now the last step is subtracting that 6 from -7.5: -7.5 - 6 =

30. anonymous

-13.5

31. anonymous

Awesome : )

32. anonymous

But if you look at the sample problem, they subtracted another part too.

33. anonymous

They subtracted the value of the expression when a 1 was plugged in. We subtracted the value of the expression when a 2 was plugged in.

34. anonymous

I got -8 and it's still wrong.

35. anonymous

-8 on which problem?

36. anonymous

Ugh. It's + 8 not +6

37. anonymous

${-3v ^{2} \over 2}+8v$

38. anonymous

39. anonymous

Okay

40. anonymous

Sorry. I thought the expressions were the same in the example and actual problems.

41. anonymous

It's okay. Can you help with another problem?

42. anonymous

If you're not busy?

43. anonymous

Sure.

44. anonymous

45. anonymous

Sample:

46. anonymous

4/3

47. anonymous

Start off exactly as the example starts by dividing u and -4 by the square root of u. This gives you: $\int\limits_{1}^{9}u ^{1/2}-4u ^{-1/2}$

48. anonymous

Then integrate each term.

49. anonymous

$[{2 \over 3}u ^{3/2}-8u ^{1/2}]$

50. anonymous

Plug in 9 first, and evaluate. Plug in 1 afterwards, then evaluate. Subtract the second answer from the first one.

51. anonymous

Take care and don't forget to mark a Best Response. Thank you