Đáp án+Giải thích các bước giải:
1)$x^2+10x+26+y^2+2y$
$=(x^2+10x+25)+(y^2+2y+1)$
$=(x+5)^2+(y+1)^2$
$2)z^2-6z+13+t^2+4t$
$=(z^2-6z+9)+(t^2+4t+4)$
$=(z-3)^2+(t+2)^2$
$3)x^2-2xy+2y^2+2y+1$
$=(x^2-2xy+y^2)+(y^2+2y+1)$
$=(x-y)^2+(y+1)^2$
$4)4x^2+2z^2-4xz-2z+1$
$=(4x^2-4xz+z^2)+(z^2-2z+1)$
$=(2x-z)^2+(z-1)^2$
$5)4x^2-12x-y^2+2y+8$
$=(4x^2-12x+9)-(y^2-2y+1)$
$=(2x-3)^2-(y-1)^2$
$6)4x^2+2z^2-4xz-2z+1$
$=(4x^2-4xz+z^2)+(z^2-2z+1)$
$=(2x-z)^2+(z-1)^2$
$7)(x+y+4)(x+y-4)$
$=(x+y)^2-4^2$
$8)(x+y+6)(x+y-6)$
$=(x+y)^2-6^2$
$9)(y+2x-3)(y-2x-3)$
$=(y-3+2x)(y-3-2x)$
$=(y-3)^2-(2x)^2$
$10)(x+2y+3z)(2y+3z-x)$
$=(2y+3z+x)(2y+3z-x)$
$=(2y+3z)^2-x^2$
Chúc bạn học tốt ~~~
