先化简,再求值1/2-a + 1/2+a - a²-4a/a²-4 ,其中a=-3 1/2-a + 1/2+a - a²-4a/a²-4 ,其中a=-3 x-y/x²-2xy+y² - xy+y²/x²-y²,其中(x-2)²+ ly+3l=0
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![先化简,再求值1/2-a + 1/2+a - a²-4a/a²-4 ,其中a=-3 1/2-a + 1/2+a - a²-4a/a²-4 ,其中a=-3 x-y/x²-2xy+y² - xy+y²/x²-y²,其中(x-2)²+ ly+3l=0](/uploads/image/z/1106801-17-1.jpg?t=%E5%85%88%E5%8C%96%E7%AE%80%2C%E5%86%8D%E6%B1%82%E5%80%BC1%2F2-a+%2B+1%2F2%2Ba+-+a%26%23178%3B-4a%2Fa%26%23178%3B-4+%2C%E5%85%B6%E4%B8%ADa%3D-3+++1%2F2-a+%2B+1%2F2%2Ba+-+a%26%23178%3B-4a%2Fa%26%23178%3B-4+%2C%E5%85%B6%E4%B8%ADa%3D-3++x-y%2Fx%26%23178%3B-2xy%2By%26%23178%3B++-++xy%2By%26%23178%3B%2Fx%26%23178%3B-y%26%23178%3B%2C%E5%85%B6%E4%B8%AD%EF%BC%88x-2%EF%BC%89%26%23178%3B%2B++ly%2B3l%3D0)
先化简,再求值1/2-a + 1/2+a - a²-4a/a²-4 ,其中a=-3 1/2-a + 1/2+a - a²-4a/a²-4 ,其中a=-3 x-y/x²-2xy+y² - xy+y²/x²-y²,其中(x-2)²+ ly+3l=0
先化简,再求值1/2-a + 1/2+a - a²-4a/a²-4 ,其中a=-3
1/2-a + 1/2+a - a²-4a/a²-4 ,其中a=-3
x-y/x²-2xy+y² - xy+y²/x²-y²,其中(x-2)²+ ly+3l=0
先化简,再求值1/2-a + 1/2+a - a²-4a/a²-4 ,其中a=-3 1/2-a + 1/2+a - a²-4a/a²-4 ,其中a=-3 x-y/x²-2xy+y² - xy+y²/x²-y²,其中(x-2)²+ ly+3l=0
1/2-a + 1/2+a - a²-4a/a²-4 ,其中a=-3
1/(2-a) + 1/(2+a) - (a²-4a)/(a²-4)
=(2+a+2-a+a²-4a)/(4-a²)
=(4+a²-4a)/(4-a²)
=(2-a)²/(2-a)(2+a)
=(2-a)/(2+a)
=(2+3)/(2-3)
= -5
x-y/x²-2xy+y² - xy+y²/x²-y²,其中(x-2)²+ ly+3l=0
(x-2)²+ ly+3l=0
x-2=0且y+3=0
则,x=2 ,y = -3
x-y/x²-2xy+y² - xy+y²/x²-y²
=1/(x-y) - y/(x-y)
=(1-y)/(x-y)
=(1+3)/(2+3)
=4/5
1/(2-a)+1/(2+a)-(a^2-4a)/(a^2-4)
=4/(4-a^2)+(a^2+4a)/(4-a^2)
=[(a+2)^2]/(4-a^2)
=(a+2/(2-a) 把a=-3代入得 -1/5
(x-y)/(x^2-2xy+y^2)-(xy+y^2)/(x^2-y^2)
=1/(x-y)-y/(x-y)
=(1-y)/(x-y) 因为(x-2)²+ |y+3|=0 所以 x=2 y=-3 并且把值代入式子中得4/5