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英语数学题求助!急!!谢谢~~
1.Findthefirstthreetermsintheexpansions,inascendingpowersofx,of(1-2x))^162.Findthecoe...
1.Find the first three terms in the expansions,in ascending powers of x,of (1-2x))^16
2.Find the coefficient of a^3b^5 in the expansions of (5a+1/2b)^8 展开
2.Find the coefficient of a^3b^5 in the expansions of (5a+1/2b)^8 展开
2个回答
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1.the first three terms of (1-2x)^16 are : 1 , -32x , 480x^2
2.the term consists of a^3b^5 is : C(8,3)*(5a)^3*(b/2)^5
so the coefficient of it is : C(8,3)*5^3 / 2^5 which is equal to 6968
2.the term consists of a^3b^5 is : C(8,3)*(5a)^3*(b/2)^5
so the coefficient of it is : C(8,3)*5^3 / 2^5 which is equal to 6968
2011-09-25
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1.Find the first three terms in the expansions,in ascending powers of x,of (1-2x))^16
2.Find the coefficient of a^3b^5 in the expansions of (5a+1/2b)^8
2.Find the coefficient of a^3b^5 in the expansions of (5a+1/2b)^8
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