a(7x-x^2)-b(5x-4x^2)=-11x^2+31x,,[equal sign 有3橫]
a&b=?
a(7x-x^2)-b(5x-4x^2)=-11x^2+31x,,a&b=?
2008-07-19 6:31 pm
回答 (1)
2008-07-19 7:41 pm
✔ 最佳答案
a(7x-x^2)-b(5x-4x^2)=7ax-ax^2-5bx+4bx^2
=(4b-a)x^2+(7a-5b)x
Since that equation is equal to -11x^2+31x,
So
-11=4b-a--(1)
31=7a+5b--(2)
7*(1)+(2):
-77+31=28b-7a+7a-5b
-46=23b
b=-2,
a=3//
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原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20080719000051KK00643