-3[y-(3x-3xy)]-[y+2(4x^2-4xy)]
问题描述：
-3[y-(3x-3xy)]-[y+2(4x^2-4xy)]
答
-3[y-(3x-3xy)]-[y+2(4x^2-4xy)]
=-3y+3(3x-3xy)-y-2(4x^2-4xy)
=-4y+9x-9xy-8x^2+8xy
=-8x^2-4y+9x-xy