(3x-y)(x+2y)最后等于多少!

网友回答

=3x²+6xy-xy-2y²
=3x²+5xy-2y²
======以下答案可供参考======
供参考答案1:
(3x-y)(x+2y)
=3x^2+6xy-xy-2y^2
=3x^2+5xy-2y^2
供参考答案2:
|3x-y+1|+(x+2y-3)的2次幂=0则3x-y+1=0①x+2y-3=0②①×2+②，得6x+2+x-3=0，解得x=1/7代入①，解得y=10/7