Engineering Board Exam Reviewer · Binomial Theorem · medium
Find the coefficient of x5 in the expansion of (2x-1)8.
- 1792
- -448
- -1024
- -1792
Answer
D. -1792
Solution
The general term is 8r(2x)8-r(-1)r. For x5, 8-r=5 r=3: 83(2)5(-1)3=56(32)(-1)=-1792.
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