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先化简再求值x-3y/x^2-9y^2其中x=3/4.y=-3/4
题目详情
先化简再求值x-3y/x^2-9y^2其中x=3/4.y=-3/4
▼优质解答
答案和解析
原式=(x-3y)/(x-3y)(x+3y)
=1/(x+3y)
=1/(3/4-3*3/4)
=1/(-3/2)
=-2/3
=1/(x+3y)
=1/(3/4-3*3/4)
=1/(-3/2)
=-2/3
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