How do you factor this cube: $\displaystyle (x+5)^3 - (2x+1)^3$
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Originally Posted by Devi09 How do you factor this cube: $\displaystyle (x+5)^3 - (2x+1)^3$ $\displaystyle (a^3-b^3)=(a-b)(a^2+ab+b^2)$ Let $\displaystyle a=x+5$ and $\displaystyle b=2x+1$. It isn't pretty!
As these are cubics you may want to consider expanding using the binomial theorem and collecting like terms. Unless, of course, you've been instructed to use the difference of two cubes
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