Q.use the binomial theorem to find the coefficient of x^5y^3 in (x-2y)^8.
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Originally Posted by kodirl Q.use the binomial theorem to find the coefficient of x^5y^3 in (x-2y)^8. The binomial theorem tell you that: $\displaystyle (x-2y)^8=\sum_{r=0}^8 {8 \choose r}x^{n-r}(-2y)^{r} $ So the coefficient of $\displaystyle x^5y^3$ is: $\displaystyle {8 \choose 3}(-2)^3=-\frac{8!\times 8}{5!\ 3!} $ RonL
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