SOLUTION: Find the coefficient of b^5 in the expansion of (a-2b)^8 My answer = 1 Not sure if thats right. If you could show me the steps to solving this problem it would be much appr

Question 307812: Find the coefficient of b^5 in the expansion of (a-2b)^8
My answer = 1
Not sure if thats right. If you could show me the steps to solving this problem it would be much appreciated. Thank You. :)
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Find the coefficient of b^5 in the expansion of (a-2b)^8
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8C3(a^3)(-2b)^5
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= [(8*7*6)/(1*2*3)](a^3)(-32)b^5
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= 56*(-32)a^3b^5
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= -1792a^3b^5
======================
Cheers,
Stan H.
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