1.把下列各式分解因式：
(1)$t^2 + 30t + 225 =$
(2)$9 - 12x + 4x^2 =$
(3)$m^2 - m + \frac{1}{4} =$
(4)$-x^2 + 4x - 4 =$
(5)$a^2 - 2\sqrt{3}a + 3 =$
(6)$x^2y^2 + 22xy + 121 =$
(1)$t^2 + 30t + 225 =$
$(t+15)^2$
；(2)$9 - 12x + 4x^2 =$
$(3-2x)^2$
；(3)$m^2 - m + \frac{1}{4} =$
$(m-\frac{1}{2})^2$
；(4)$-x^2 + 4x - 4 =$
$-(x-2)^2$
；(5)$a^2 - 2\sqrt{3}a + 3 =$
$(a-\sqrt{3})^2$
；(6)$x^2y^2 + 22xy + 121 =$
$(xy+11)^2$
。答案：1.(1)$(t+15)^2$
(2)$(3-2x)^2$
(3)$(m-\frac{1}{2})^2$
(4)$-(x-2)^2$
(5)$(a-\sqrt{3})^2$
(6)$(xy+11)^2$
(2)$(3-2x)^2$
(3)$(m-\frac{1}{2})^2$
(4)$-(x-2)^2$
(5)$(a-\sqrt{3})^2$
(6)$(xy+11)^2$
2. 把下列各式分解因式：
(1) $6xy - x^2 - 9y^2$；
(2) $4x^2 - 3y(4x - 3y)$；
(3) $\frac{1}{2}m^2 - mn + \frac{1}{2}n^2$；
(4) $(x^2 + 4)^2 - 16x^2$；
(5) $4x^2y^2 - (x^2 + y^2)^2$；
(6) $a^4 - 2a^2b^2 + b^4$；
(7) $9(x - 2)^2 - 6(x - 2) + 1$；
(8) $x^4 - 18x^2 + 81$；
(9) $1 - 2(x - y) + (x - y)^2$；
(10) $(x - 2y)^2 + 8xy$；
(1) $6xy - x^2 - 9y^2$；
(2) $4x^2 - 3y(4x - 3y)$；
(3) $\frac{1}{2}m^2 - mn + \frac{1}{2}n^2$；
(4) $(x^2 + 4)^2 - 16x^2$；
(5) $4x^2y^2 - (x^2 + y^2)^2$；
(6) $a^4 - 2a^2b^2 + b^4$；
(7) $9(x - 2)^2 - 6(x - 2) + 1$；
(8) $x^4 - 18x^2 + 81$；
(9) $1 - 2(x - y) + (x - y)^2$；
(10) $(x - 2y)^2 + 8xy$；
答案：2.(1)$-(x-3y)^2$
(2)$(2x-3y)^2$
(3)$\frac{1}{2}(m-n)^2$
(4)$(x+2)^2(x-2)^2$
(5)$-(x+y)^2(x-y)^2$
(6)$(a+b)^2(a-b)^2$
(7)$(3x-7)^2$
(8)$(x-3)^2(x+3)^2$
(9)$(x-y-1)^2$
(10)$(x+2y)^2$
(2)$(2x-3y)^2$
(3)$\frac{1}{2}(m-n)^2$
(4)$(x+2)^2(x-2)^2$
(5)$-(x+y)^2(x-y)^2$
(6)$(a+b)^2(a-b)^2$
(7)$(3x-7)^2$
(8)$(x-3)^2(x+3)^2$
(9)$(x-y-1)^2$
(10)$(x+2y)^2$