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which term in the expansion of \bigg( {x}^{2} - \dfrac{1}{x} \bigg)^{9}(x 2 − x 1 ​ ) 9 will be independent of heads also find that term ​

answers: 1
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Answer:

Answer:

eg

Correct option is

D

−36

(

60

1

81

x

8

)⋅(2x

2

x

2

3

)

6

60

1

(2x

2

x

2

3

)

6

81

1

⋅x

8

(2x

2

x

2

3

)

6

its general term

$$\dfrac {1}{60}\ ^{6}C_{r} 2^{6 - r} (-3)^{r}x^{12 -4 r} - \dfrac {1}{81} \^{6}C_{r} 2^{6 - r} (-3)^{r} x^{20 - 4r}$$

12−4r=0 20−4r=0

r=3 r=5

for term independent of x,r for 1

st

expression is 3 and r for 2

nd

expression is 5

60

1

6

C

3

×2

3

×3

3

+

81

1

6

C

5

×2×3

5

−72+36=−36

∴ term independent of x=−36.

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