## Dodo1 one year ago curve problems?

1. Dodo1

2. Luigi0210

Do you know what the graph looks like?

3. Dodo1

No, I have no idea!

4. Luigi0210

Well it might be a good idea to sketch a graph

5. Dodo1

would it possible to solve the problem　without a graph?

6. Dodo1

would it be

7. Luigi0210

Well yes but it be a bit harder since we don't know which graph is higher

8. Dodo1

oh i see... how do you draw a graph

9. Luigi0210

wait, are you finding total area or net area?

10. Dodo1

it says find the area between the curves?

11. Luigi0210

If I'm not mistaken then the graphs should look like this when graphed |dw:1366855841011:dw|

12. Dodo1

sin and cos graph?

13. Luigi0210

Uhm no, the ends of the graph go off into infinity after they have intersected

14. Dodo1

Oh.

15. Luigi0210

Now, do you notice anything about the two graphs?

16. Dodo1

-they get smaller and smaller? -they intersects

17. Luigi0210

Well yes but also they are reflections of one another

18. Dodo1

Yes,

19. Luigi0210

So that means that whatever area on graph has the other has the opposite area. Such as -x and x.

20. Dodo1

Yes,

21. Luigi0210

So that means the area would be zero

22. Dodo1

23. Dodo1

i thought i need more calculations

24. Luigi0210

Well you could if you want but the answer would still be zero. These two graphs are going to cancel each others area out

25. Dodo1

i entered zero into the answer but it tells me that it was wrong

26. Luigi0210

Well let's solve it right now, do you know how to set it up as an integral?

27. Dodo1

No, I have no idea!!

28. Dodo1

@Luigi0210

29. Luigi0210

Sorry I was trying to evaluate the problem

30. Luigi0210

but anyways we would set up the problem like this: $\int\limits_{0}^{9} (x^3-14x^2+45x)-(-x^3+14x^2-45x) dx$

31. Zarkon

I'm betting that they want you to set up two different integrals...based on the two enclosed regions.

32. Dodo1

so between...= minus. i got it

33. Luigi0210

Setting up two equations would take a bit longer

34. Zarkon
35. Dodo1

whats next step?

36. Luigi0210

The answer I got was 253/2..

37. Luigi0210

*243/2

38. Dodo1

the answer was wrong but thanks for ur help!

39. Luigi0210