Đáp án:
Giải thích các bước giải:
$h, x²+6x+9-y²=(x+3)²-y²=(x+3-y). (x+3+y)\\ i, 81-x²+2xy-y²=9²-(x²-2xy+y²)=9²-(x-y)²=(9-x+y).(9-x-y)\\ j, xz+yz-5(x+y)=xz+yz-5x-5y=z(x+y)-5(x+y)=(z-5).(x+y)\\ k, 3x²-3xy-5x+5y=3x(x−y)−5(x−y)=(x−y)(3x−5)\\ l, x²+4x-y²+4=(x²+4x+4)−y²=(x+2)²−y²=(x+2−y)(x+2+y)\\ m, 3x²+6xy+3y²-3z²= 3(x² + 2xy +y² -z²)=3[(x² + 2xy +y²)-z²]=3[(x+y)² -z²]=3.(x+y-z).(x+y+z)\\ r,x²+5x+6=x²+2x+3x+6=x(x+2)+3(x+2)=(x=2).(x+3)\\ s, x²-4x+3=x²-3x-1x+3=x(x-3)-1(x-3)=(x-3).(x-1)\\ w, x^4y^4+4=(x^4y^4+4x²y²+4)-4x²y=(x²y²+2)²-(2xy)²=(x²y²+2-2xy).(x²y²+2+2xy)$
câu `q,u,v` quên cách làm rùi
