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`        The coefficient of x^3 in the expansion of (1+3x)^2 / 1-2x will be?Ans: 50`
5 months ago

```							we know thw identity: (1 – y)^(-1)= 1+y+y^2+y^3+..................so,  (1+3x)^2 / (1-2x )=  (1+3x)^2*(1 – 2x)^(-1)= (1+6x+9x^2)*(1+2x+4x^2+8x^3+.........)so, coeff of x^3 is 1*8 + 6*4 + 9*2= 26+24= 50kindly approve :)
```
5 months ago
```							Dear student it can be written as ( 1 + 9x^2 + 6x) (1 – 2x)^-1  = ( 1 + 9x^2 + 6x) ( 1 + 2x + 4x^2 + 8x^3+ …..) hence coefficient of x3 = 8 + 18 + 24 = 50
```
5 months ago
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