Question

In the expansion of (x/2-3/x^2)^10 the coefficient of x^4 is

Answer 1

Tr+1=ⁿCr (a)^(n-r)b^r

Tr+1=10Cr(x/2)(10-r)(3/x²)^r

cofficient of x⁴ so 10-r=4

r=6

T6+1=10C6(x/2)^(10-6)(3/x²)^6

T7= 10C6(x⁴/16)(3/x²)^6

cofficient of x⁴= 10C6 (3/x²)^6

= 210×729/x^12

153090/x^12

I hope this will help you

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