## anonymous 5 years ago trapezoidal rule

1. anonymous

solve: $\int\limits_{9}^{16}\sqrt{x}$

2. anonymous

this is my approach but its not getting me the right answer: $\int\limits_{9}^{16{x}}\sqrt{x}\approx \int\limits_{9}^{10}\sqrt{x}+ \int\limits_{10}^{11}\sqrt{x}+\int\limits_{11}^{12}\sqrt{x}+\int\limits_{12}^{13}\sqrt{x}+\int\limits_{13}^{14}\sqrt{x}+\int\limits_{14}^{15}\sqrt{x}+\int\limits_{15}^{16}\sqrt{x}$

3. anonymous

$\approx 1/2(3+\sqrt{10}) + 1/2(\sqrt{10}+\sqrt{11}) + 1/2(\sqrt{11}+\sqrt{12}) + 1/2(\sqrt{12}+\sqrt{13}) + 1/2(\sqrt{13}+\sqrt{14}) + 1/2(\sqrt{14}+\sqrt{15}) +1/2(\sqrt{15}+4)$

4. watchmath

Hi and, please write down the problem.

5. anonymous

solve using the trapezoidal rule: $\int\limits_{9}^{16}\sqrt{x}$ rounding to three significant figures

6. watchmath

into how many sub intervals?

7. anonymous

my answer is 20.9 and the answer in the text book is 27.9

8. anonymous

i dont know where i went wrong this time

9. anonymous

8 sub intervals

10. anonymous

sorry 7 intervals

11. watchmath
12. watchmath

Could you post the complete question exactly like what you have on your book?

13. anonymous

ok one second

14. anonymous

(a)complete this table of values for the function$y=\sqrt{x}$ x 9 10 11 12 13 14 15 16 y (b) use the trapezoidal rule with the eight function values above to estimate $\int\limits_{9}^{16}\sqrt{x}$ give your answers correct to three significant figures

15. anonymous

wait you answer is right lol i rechecked the answer its 24.7

16. watchmath

:D

17. anonymous

sorry lol can u see where i went wrong

18. watchmath

I am not sure, but it seems you forgot to add one of the expression when you plug in into your calculator.

19. anonymous

ok ill try it out again

20. anonymous

lol your right i left out one expression its 1 o clock in the morning lol im doing alot of stupid mistakes