## anonymous 5 years ago Evaluate: I will post problem

1. anonymous

$\int\limits_{-1}^{3} (3x-5)^4$

2. anonymous

I get to 1/24(3x-5)^8

3. anonymous

this is before I substitute

4. anonymous

1st I get u=3x-5 3dc= 1/3 du

5. anonymous

the dc is dx

6. anonymous

Where are you getting 1/24 and ^8?

7. anonymous

never mind the 1/24 and 1/8 I looked at something else as I was writing. I will redo this one first

8. anonymous

how about 1/15(3x-5)^5 does that look better? I really unsure about what I am doing.

9. anonymous

this answer is before I substitute

10. anonymous

Yeah, that looks right

11. anonymous

$\int\limits (3x-5)^4 \, dx = -\frac{1}{15} (5-3 x)^5$ $\int\limits_{-1}^3 (3x-5)^4 \, dx= \frac{11264}{5}$ $\left(-\frac{1}{15} (5-3 x)^5\text{/.}x\to 3\right)-\left(-\frac{1}{15} (5-3 x)^5\text{/.}x\to -1\right)=\frac{11264}{5}$

12. anonymous

Good example to follow. (You miswrote the problem.

13. anonymous

why did you switch to 5-3x and not keep it as 3x-5

14. anonymous

typo

15. anonymous

where did I miswrite the problem? The only thing I left off was the dx at the end

16. anonymous

Not you Robto

17. anonymous

ok

18. anonymous

now I think I should have 1/15(3(3)-5)^4 - 1/15(3(-1)-5)^4 1/15(16) - 1/15(4096) is that correct so far??

19. anonymous

Processing chaguanas's statement.

20. anonymous

?

21. anonymous

are you still there

22. anonymous

what's wrong?

23. anonymous

did you see the last post I made What I think I should have after substitution

24. anonymous

Your process is right. I don't have to check the minutia, that part is all arithmetic. Put you are inputting -1. The writing is very small on the original problem is the low end point 1 or -1?

25. anonymous

-1 I was just checking because the problem asks to express as a decimal, approximate to one decimal place. After I do the problem I get -272. I thought I might be doing it wrong.

26. anonymous

Approximate to one decimal place, tells you nothing of the answer. It is instructions on how to write your answer. Assuming that is the right answer, to one decimal place is -272.0

27. anonymous

ok I was just thinking the answer would be different

28. anonymous

mom: Way to go mom. No ambiguity in your problem statement. chaguanas: $-\frac{1}{15} (5-3 x)^5 = \frac{1}{15} (3 x-5)^5$ I am using the Mathematica program, version 8, to solve this and that on this web site. With Mathematica at my disposal I am not about to solve anything related to mathematics with pencil and paper. Mathematica has been in development for some years now. In the early years the developers made some decisions regarding the input language construction and what they would deliver for output forms (answers). One thing that "does not look right" is that their polynomial answers are printed with the exponents, in the exponential terms, ordered low to high, not high to low as presented on school chalk/white boards. At first that was annoying for me but soon one adjusts and excepts their formulations. Probably the tendency for some inexperienced math students is to conclude that because a polynomial as written "doesn't look right", it must be inherently wrong and conveys the wrong intent.