Đáp án:
$ a,(x-2)^2 +(x-2)^2$
$= 2(x-2)^2$
$ = 2(x^2-4x+4)$
$ = 2x^2 -8x +8$
$b) (x-2)(x+2)+(x-2)^2 +(x+2)^2$
$ = x^2 - 4 + x^2 -4x +4 +x^2+4x+4$
$ = x^2 +x^2 +x^2 -4x +4x -4 +4 +4$
$ = 3x^2 +4$
$c, (x-3)^2 +(x+3)^2 +(x-3)(x+3)$
$ =x^2 -6x +9 + x^2 +6x+9 + x^2 -9$
$ = x^2 +x^2 +x^2 -6x +6x +9+9 -9$
$ = 3x^2 +9$