1.解方程组.(x+2)平方-(y-3)平方=(x+y)(x-y),x-3y=22.化简求值.(1) 已知(x-y)平方=625/36,x+y=7/6,求xy+4的值(2)已知a-b=2,b-c=-3,c-d=5,求代数式(a-c)(b-d)/(a-d)
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![1.解方程组.(x+2)平方-(y-3)平方=(x+y)(x-y),x-3y=22.化简求值.(1) 已知(x-y)平方=625/36,x+y=7/6,求xy+4的值(2)已知a-b=2,b-c=-3,c-d=5,求代数式(a-c)(b-d)/(a-d)](/uploads/image/z/10226571-51-1.jpg?t=1.%E8%A7%A3%E6%96%B9%E7%A8%8B%E7%BB%84.%EF%BC%88x%2B2%EF%BC%89%E5%B9%B3%E6%96%B9-%EF%BC%88y-3%EF%BC%89%E5%B9%B3%E6%96%B9%3D%EF%BC%88x%2By%EF%BC%89%EF%BC%88x-y%EF%BC%89%2Cx-3y%3D22.%E5%8C%96%E7%AE%80%E6%B1%82%E5%80%BC.%EF%BC%881%EF%BC%89+%E5%B7%B2%E7%9F%A5%EF%BC%88x-y%EF%BC%89%E5%B9%B3%E6%96%B9%3D625%2F36%2Cx%2By%3D7%2F6%2C%E6%B1%82xy%2B4%E7%9A%84%E5%80%BC%EF%BC%882%EF%BC%89%E5%B7%B2%E7%9F%A5a-b%3D2%2Cb-c%3D-3%2Cc-d%3D5%2C%E6%B1%82%E4%BB%A3%E6%95%B0%E5%BC%8F%EF%BC%88a-c%EF%BC%89%EF%BC%88b-d%EF%BC%89%2F%EF%BC%88a-d%EF%BC%89)
1.解方程组.(x+2)平方-(y-3)平方=(x+y)(x-y),x-3y=22.化简求值.(1) 已知(x-y)平方=625/36,x+y=7/6,求xy+4的值(2)已知a-b=2,b-c=-3,c-d=5,求代数式(a-c)(b-d)/(a-d)
1.解方程组.(x+2)平方-(y-3)平方=(x+y)(x-y),
x-3y=2
2.化简求值.
(1) 已知(x-y)平方=625/36,x+y=7/6,求xy+4的值
(2)已知a-b=2,b-c=-3,c-d=5,求代数式(a-c)(b-d)/(a-d)
1.解方程组.(x+2)平方-(y-3)平方=(x+y)(x-y),x-3y=22.化简求值.(1) 已知(x-y)平方=625/36,x+y=7/6,求xy+4的值(2)已知a-b=2,b-c=-3,c-d=5,求代数式(a-c)(b-d)/(a-d)
1.
(x+2)^2-(y-3)^2=(x+y)(x-y)...(1)
x-3y=2...(2)
由(2)得x=3y+2...(3),将(3)代入(1)得:
(3y+4)^2-(y-3)^2=(4y+2)(2y+2),解得:
y=-1/6...(4),
代入(2)得:
x=3/2
2.1
(X-Y)^2
=X^2+2XY+Y^2-4XY
=(X+Y)^2-4XY
=49/36-4XY
=625/36XY
=-4
所以XY+4=-4+4=0
2.2
a-b=2,b-c=-3,c-d=5
a-c=(a-b)+(b-c)=2-3=-1
b-c=(b-c)+(c-d)=-3+5=2
a-d=(a-b)+(b-c)+(c-d)=2-3+5=4
所以
(a-c)(b-d)/(a-d)=-1/2
1、(x+2)2-(y-3)2=(x+y)(x-y)
x2+4x+4-y2+6y-9=x2- y2
4x+6y=-4
2 x+3y=-2
因为x-3y=2
所以x=2+3y,带入原式,得出:
2*(2+3y)+3y =-2
y=-2/3
所以:x=0
(x+2)平方-(y-3)平方=(x+y)(x-y)
x^+4+4x-y^-9-6y=x^-xy+xy-y^
x^+4x-y^-5+6y=x^-y^
4x+6y=5
代入x=2+3y
得y=-1/6
x=1又1/2
二: (x+y)^=625/36
得(x+y)=25/6
x=25/6+y代入x+y=7/6
得y=-3/2
x=8/3
得xy+4=0
1、x=2+3y代入上式的(3y+4)^2-(y-3)^2=(2+4y)(2+2y)得y=-1/6则x=3/2
2、(1)由x+y=7/6得 (x+y)^2=49/36则(x+y)^2-(x-y)^2=4xy=49/36-625/36即xy=-4则xy+4=0
(2)a-c=(a-b)-(b-c)=5,b-d=(b-c)-(b-d)=-8,a-d=(a-b)-(b-d0=10,则(a-c)(b-d)/(a-d)=5×(-8)/10=-4