Question

the coefficient of x³ in the expansion of (2x) (1-3x)⁶ is 405. find a.​

Answer 1

Step-by-step explanation:

−30

(1−x+x2)5

General term:- α1!α2!α35!1α1(−1)α2xα2(x2)α3

=α1!α2!α3!5!(−1)α2xα2+2α3

For coefficient of x3

α2+2α3=3

α1+α2+α3=5

α3=0,α2=3,α1=2

α3=1,α2=1,α1=3

∴ coefficient of x3=2!3!0!5!(−1)3+3!1!1!5!(−1)1

=−25×4−5×4

=10−20

=−30.

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Answer 2

Answer:

The question is incorrect

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