If-x-y-1-then-r-0-n-r-2-n-C-r-x-r-y-n-r-equals-

Question Number 56139 by gunawan last updated on 11/Mar/19

If x + y = 1, then \underset{r = 0}{\sum^{n}} r^{2}^{n} C_{r} x^{r} y^{n - r} equals

Answered by tanmay.chaudhury50@gmail.com last updated on 11/Mar/19

{(y + x)}^{n} = 1

{n c}_{0} y^{n - 0} x^{0} + {n c}_{1} y^{n - 1} x^{1} + {n c}_{2} y^{n - 2} x^{2} + \dots + {n c}_{n} y^{n - n} x^{n}

{(y + x)}^{n} = 1 = \underset{r = 0}{\sum^{n}} {n c}_{r} y^{n - r} x^{r}

w a i t \dots p l s \dots