## hiralpatel121 Group Title Can someone help me solve this calc problem? It's attached. 2 years ago 2 years ago

1. hiralpatel121 Group Title

2. hiralpatel121 Group Title

Sample problem:

3. myko Group Title

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

4. hiralpatel121 Group Title

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

5. coreylvaughn Group Title

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

6. coreylvaughn Group Title

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

7. coreylvaughn Group Title

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. hiralpatel121 Group Title

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

9. coreylvaughn Group Title

Yes.

10. hiralpatel121 Group Title

I got 77.5 when I plugged in 5.

11. coreylvaughn Group Title

I got -7.5

12. coreylvaughn Group Title

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

13. coreylvaughn Group Title

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

14. hiralpatel121 Group Title

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

15. coreylvaughn Group Title

No. 4.5.

16. coreylvaughn Group Title

Look at the equation I wrote above.

17. coreylvaughn Group Title

What do you get when you evaluate that expression?

18. hiralpatel121 Group Title

Oh, I forgot to square it.

19. hiralpatel121 Group Title

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

20. coreylvaughn Group Title

It's cool.

21. hiralpatel121 Group Title

It's not correct though.

22. coreylvaughn Group Title

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. coreylvaughn Group Title

6 and 1 are solely used in the example.

24. coreylvaughn Group Title

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

25. hiralpatel121 Group Title

-7.5

26. coreylvaughn Group Title

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

27. coreylvaughn Group Title

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

28. hiralpatel121 Group Title

6

29. coreylvaughn Group Title

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

30. hiralpatel121 Group Title

-13.5

31. coreylvaughn Group Title

Awesome : )

32. hiralpatel121 Group Title

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

33. coreylvaughn Group Title

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. hiralpatel121 Group Title

I got -8 and it's still wrong.

35. coreylvaughn Group Title

-8 on which problem?

36. coreylvaughn Group Title

Ugh. It's + 8 not +6

37. coreylvaughn Group Title

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

38. coreylvaughn Group Title

39. hiralpatel121 Group Title

Okay

40. coreylvaughn Group Title

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

41. hiralpatel121 Group Title

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

42. hiralpatel121 Group Title

If you're not busy?

43. coreylvaughn Group Title

Sure.

44. hiralpatel121 Group Title

45. hiralpatel121 Group Title

Sample:

46. coreylvaughn Group Title

4/3

47. coreylvaughn Group Title

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. coreylvaughn Group Title

Then integrate each term.

49. coreylvaughn Group Title

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

50. coreylvaughn Group Title

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

51. coreylvaughn Group Title

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