In-the-binomial-expasion-of-a-b-5-the-sum-of-2-nd-and-3-rd-term-is-zero-then-a-b-is-

Question Number 22612 by Tinkutara last updated on 21/Oct/17

I n t h e b i n o m i a l e x p a s i o n o f {(a - b)}^{5},

t h e s u m o f 2^{n d} a n d 3^{r d} t e r m i s z e r o,

t h e n \frac{a}{b} i s

Answered by ajfour last updated on 21/Oct/17

\Rightarrow - 5 a^{4} b + 10 a^{3} b^{2} = 0

\Rightarrow \frac{a}{b} = 2 .

Commented by Tinkutara last updated on 21/Oct/17

B u t i n b o o k a n s w e r g i v e n i s \frac{1}{2} . I s t h i s

w r o n g ?

Answered by ajfour last updated on 21/Oct/17

{(a - b)}^{5} = - {(b - a)}^{5}

s u m o f 2^{n d} a n d 3^{r d} t e r m

= 5 b^{4} a - 10 b^{3} a^{2} = 0

\Rightarrow \frac{a}{b} = \frac{1}{2} .

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