Bài 1.
a) $x^{2}$ + 4x +4
= $(x + 2)^{2}$
b) $x^{2}$ - 8x + 16
= $(x - 4)^{2}$
c) (x + 5)(x - 5)
= $x^{2}$ - $5^{2}$
= $x^{2}$ - 25
h) $x^{2}$ + 2x +1
= $(x + 1)^{2}$
i) $x^{2}$ - 1
= (x + 1)(x - 1)
k) $x^{2}$ + 6x + 9
= $(x + 3)^{2}$
j) $4x^{2}$ - 9
= (2x + 3)(2x - 3)
m) $16x^{2}$ - 8x + 1
= $(4x - 1)^{2}$
n) $9x^{2}$ + 6x +1
= $(3x + 1)^{2}$
o) $36x^{2}$ + 36x + 9
= $(6x + 3)^{2}$
Bài 2.
a) $(2x + 3y)^{2}$
= $4x^{2}$ + 12xy + 9$y^{2}$
b) $(5x - y)^{2}$
= 25$x^{2}$ - 10xy + $y^{2}$
c) $(2x + y^{2}$ )²
= $4x^{2}$ + 4x$y^{2}$ + $y^{4}$
