✔ 最佳答案
1.(2x+3y)^2-8x^2-12xy
=(2x+3y)^2-(8x^2+12xy)
=(2x+3y)^2-4x(2x+3y)
=(2x+3y)*[(2x+3y)-4x]
=(2x+3y)(-2x+3y)
2.(2x+3y)^2-8x^2-12xy-2x+3y
=(2x+3y)^2-(8x^2+12xy)-(2x-3y)
=(2x+3y)^2-4x(2x+3y)-(2x-3y)
=(2x+3y)*[(2x+3y)-4x]+(-2x+3y)
=(2x+3y)(-2x+3y)+(-2x+3y)
=(2x+3y+1)(-2x+3y)