1.find the coefficient of x in the expansion of (3x-1)(4x+7)??
A.25
B.21
C.17
D.13
Please show the answer and the steps clearly!THX!
maths(20pts)!!(MC)
2007-03-20 5:48 am
回答 (3)
2007-03-20 5:53 am
(3x-1)(4x+7)= 12x^2 + 21x - 4x - 7
= 12x^2 + 17x -7
so the coefficient of x is 17
= 12x^2 + 17x -7
so the coefficient of x is 17
2007-03-20 5:51 am
(3x-1)(4x+7)=12x^2+17x-7
Therefore, C is the answer.
Therefore, C is the answer.
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