Find the coefficient of x5 in (x + 3)8

Asked by Abhisek | 1 year ago |  65

##### Solution :-

The general term Tr+1 in the binomial expansion is given by Tr+1 = r an-r br

Here x5 is the Tr+1 term so a= x, b = 3 and n =8

Tr+1 = 8Cr x8-r 3r…………… (i)

For finding out x5

We have to equate x5= x8-r

⇒ r= 3

Putting value of r in (i) we get

$$T_{3+1}= ^8C_3x^{8-3}3^3$$

$$T_4=\dfrac{8!}{3!5!}\times x^5\times 27$$

= 1512 x5

Hence the coefficient of x5= 1512

Answered by Pragya Singh | 1 year ago

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