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## diamondboy one year ago Question

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1. diamondboy

|dw:1442085598415:dw|

2. diamondboy

@Ashleyisakitty

3. diamondboy

Could you please help me out @IrishBoy123

4. IrishBoy123

|dw:1442085754297:dw|

5. IrishBoy123

|dw:1442085839354:dw|

6. IrishBoy123

it's worth doing this first!

7. diamondboy

|dw:1442085908400:dw|

8. IrishBoy123

IOW, you can do loads of boring subs or you can start spotting these patterns and start doing integration in your head pretty much

9. diamondboy

|dw:1442086164257:dw|

10. IrishBoy123

|dw:1442086191680:dw|

11. diamondboy

+C

12. diamondboy

Is this the answer?

13. IrishBoy123

|dw:1442086517027:dw| adjustment needed?

14. Jhannybean

$\sf \int \frac{2x^2}{\sqrt{5+x^3}}dx\implies 2\int \frac{x^2}{\sqrt{5+x^3}}dx$$\sf u=5+x^3 ~,~ du = 3x^2dx \implies \frac{du}{3}=x^2dx$resub. $\sf \frac{2}{3}\int \frac{du}{u^{1/2}}$

15. diamondboy

I finally got the answer

16. diamondboy

yep @Jhannybean that was exactly how I did it.

17. Jhannybean

I'm getting $$\dfrac{2}{3}$$ and @IrishBoy123 is getting $$\dfrac{3}{2}$$?

18. diamondboy

I got 4/3 (after final simplification)

19. IrishBoy123

no! |dw:1442086992183:dw|

20. diamondboy

Thanks guys tho that was my final attempt

21. Jhannybean

$\sf 2\int\frac{1}{u^{1/2}} \cdot \frac{du}{3}= \frac{2}{3}\int\frac{du}{u^{1/2}}$Oh okay

22. Jhannybean

I thought I was making errors.... just woke up.

23. IrishBoy123

|dw:1442087204185:dw| |dw:1442087262250:dw| lol!!!!

24. Jhannybean

You spot patterns after you do a whole bunch of boring subs :P It's been years since ive done techniques of integration lol.

25. IrishBoy123

@Jhannybean agreed!

26. diamondboy

alright I believe none of u need anymore medals

27. diamondboy

Thanks guys

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