1.已知x^2-y^2=40,x+y=8/5,求x-y的.2.下列计算正确的是 ( )A.(1/2+a)(-a+1/2)=a^2-1/4B.(-x-1)(x+1)=x^2-1C.-(x-a)(-x-a)=x^2-a^2D.(-a-9)(-9+a)=-81-a^23.(x-2y)^2=(x+2y)^2+A,则A等于 ( )A.4xy B.-4xyC.8xy D.-8xy明天之前就要!
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![1.已知x^2-y^2=40,x+y=8/5,求x-y的.2.下列计算正确的是 ( )A.(1/2+a)(-a+1/2)=a^2-1/4B.(-x-1)(x+1)=x^2-1C.-(x-a)(-x-a)=x^2-a^2D.(-a-9)(-9+a)=-81-a^23.(x-2y)^2=(x+2y)^2+A,则A等于 ( )A.4xy B.-4xyC.8xy D.-8xy明天之前就要!](/uploads/image/z/13072275-27-5.jpg?t=1.%E5%B7%B2%E7%9F%A5x%5E2-y%5E2%3D40%2Cx%2By%3D8%2F5%2C%E6%B1%82x-y%E7%9A%84.2.%E4%B8%8B%E5%88%97%E8%AE%A1%E7%AE%97%E6%AD%A3%E7%A1%AE%E7%9A%84%E6%98%AF+%EF%BC%88+%EF%BC%89A.%281%2F2%2Ba%29%28-a%2B1%2F2%29%3Da%5E2-1%2F4B.%28-x-1%29%28x%2B1%29%3Dx%5E2-1C.-%28x-a%29%28-x-a%29%3Dx%5E2-a%5E2D.%28-a-9%29%28-9%2Ba%29%3D-81-a%5E23.%28x-2y%29%5E2%3D%28x%2B2y%29%5E2%2BA%2C%E5%88%99A%E7%AD%89%E4%BA%8E+%EF%BC%88+%EF%BC%89A.4xy+B.-4xyC.8xy+D.-8xy%E6%98%8E%E5%A4%A9%E4%B9%8B%E5%89%8D%E5%B0%B1%E8%A6%81%21)
1.已知x^2-y^2=40,x+y=8/5,求x-y的.2.下列计算正确的是 ( )A.(1/2+a)(-a+1/2)=a^2-1/4B.(-x-1)(x+1)=x^2-1C.-(x-a)(-x-a)=x^2-a^2D.(-a-9)(-9+a)=-81-a^23.(x-2y)^2=(x+2y)^2+A,则A等于 ( )A.4xy B.-4xyC.8xy D.-8xy明天之前就要!
1.已知x^2-y^2=40,x+y=8/5,求x-y的.
2.下列计算正确的是 ( )
A.(1/2+a)(-a+1/2)=a^2-1/4
B.(-x-1)(x+1)=x^2-1
C.-(x-a)(-x-a)=x^2-a^2
D.(-a-9)(-9+a)=-81-a^2
3.(x-2y)^2=(x+2y)^2+A,则A等于 ( )
A.4xy B.-4xy
C.8xy D.-8xy
明天之前就要!
1.已知x^2-y^2=40,x+y=8/5,求x-y的.2.下列计算正确的是 ( )A.(1/2+a)(-a+1/2)=a^2-1/4B.(-x-1)(x+1)=x^2-1C.-(x-a)(-x-a)=x^2-a^2D.(-a-9)(-9+a)=-81-a^23.(x-2y)^2=(x+2y)^2+A,则A等于 ( )A.4xy B.-4xyC.8xy D.-8xy明天之前就要!
1.
x^2-y^2=(x+y)(x-y)=40
已知(x+y)=8/5
x-y=40/(8/5)=25
2.
选C
3.
选D
第1题 : x-y=25
第2题:C
第3题:D
2c3d
第1题 : x-y=(x^2-y^2)/(x+y)=25
第2题:C
第3题:D
1、25
2、C
3、D
第1题 : x-y=(x^2-y^2)/(x+y)=25
第2题:C
第3题:D