已知A=(2x+y)/(x²-2xy+y²)*(x-y) (1)化简A (2)若x²-6xy+9y²=0,求A的值
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(1)
A=(2x+y)/(x²-2xy+y²)×(x-y)
=(2x+y)/(x-y)²×(x-y)
=(2x+y)/(x-y)
(2)∵x²-6xy+9y²=0
∴(x-3y)²=0
∴x-3y=0
∴x=3y
把x=3y代入A
A=(2x+y)/(x-y)=(2×3y+y)/(3y-y)
=(6y+y)/2y=7y/2y=7/2
A=(2x+y)/(x²-2xy+y²)×(x-y)
=(2x+y)/(x-y)²×(x-y)
=(2x+y)/(x-y)
(2)∵x²-6xy+9y²=0
∴(x-3y)²=0
∴x-3y=0
∴x=3y
把x=3y代入A
A=(2x+y)/(x-y)=(2×3y+y)/(3y-y)
=(6y+y)/2y=7y/2y=7/2
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A = [(2x+y)/(x²-2xy+y²)]*(x-y) = [(2x+y)/(x-y)²]*(x-y) = (2x+y)/(x-y)
x²-6xy+9y² = 0 , (x-3y)² = 0, x-3y = 0, x = 3y, A = (6y+y)/(3y-y) = 7/2
x²-6xy+9y² = 0 , (x-3y)² = 0, x-3y = 0, x = 3y, A = (6y+y)/(3y-y) = 7/2
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