来自刘玉忠的问题
初二数学上学期一道化简求值题化简求值(x-y)(x+y)+(x-y)^2-(x-2y)^2,其中x=-1/3,y=3
初二数学上学期一道化简求值题
化简求值
(x-y)(x+y)+(x-y)^2-(x-2y)^2,其中x=-1/3,y=3
1回答
2020-03-3015:47
初二数学上学期一道化简求值题化简求值(x-y)(x+y)+(x-y)^2-(x-2y)^2,其中x=-1/3,y=3
初二数学上学期一道化简求值题
化简求值
(x-y)(x+y)+(x-y)^2-(x-2y)^2,其中x=-1/3,y=3
(x-y)(x+y)+(x-y)^2-(x-2y)^2
=x^2-y^2+x^2-2xy+y^2-(x^2-4xy+4y^2)
=x^2+2xy-4y^2
=(-1/3)^2+2*(-1/3)*3-4*3^2
=1/9-2-36
=-37又8/9