Hello all, The problem is this: = I worked it out like this: $\displaystyle x^4/4 = 2b^4/4 - b^4/4$ But when I enter that in, they say I am wrong. Does anybody see what I'm doing wrong on this?
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Originally Posted by JohnJames Hello all, The problem is this: = I worked it out like this: $\displaystyle x^4/4 = 2b^4/4 - b^4/4$ But when I enter that in, they say I am wrong. Does anybody see what I'm doing wrong on this? You have to use brackets in the last line: $\displaystyle \left[\dfrac{x^4}4\right]^{2b}_b = \dfrac{(2b)^4}4-\dfrac{b^4}4 = \dfrac{15b^4}4$
Originally Posted by JohnJames Hello all, The problem is this: = I worked it out like this: $\displaystyle x^4/4 = 2b^4/4 - b^4/4$ But when I enter that in, they say I am wrong. Does anybody see what I'm doing wrong on this? $\displaystyle \int_{b}^{2b}x^{3}dx=\left[ \frac{x^{4}}{4}+c\right]^{2b}_{b}=\frac{(2b)^{4}}{4}+c-(\frac{b^{4}}{4}+c)=4b^{4}-\frac{b^{4}}{4}=\frac{15b^{4}}{4}$
Last edited by coscos; Jul 13th 2010 at 09:50 AM. Reason: there you go
Oh Wow, simple math got me this time lol, thanks to earboth and coscos