因式分解.1.(a^2-6a)^2+14(a^2-6a)+45 2.(x^2-10)(2^2+5)+54 计算 (x^2-1/9)/(6x-2)*(3x+1)

1.(a^2-6a)^2+14(a^2-6a)+45 [十字相乘]
=(a²-6a+9)(a²-6a+4)
2.(x^2-10)(x^2+5)+54 [十字相乘]
=(x²-10)²+15(x²-10)+54
=(x²-10+7)(x²-10+8)
=(x²-2)(x²-3)
3.(x^2-1/9)/(6x-2)*(3x+1) [乘法公式]
=(x+1/3)(x-1/3)/18(x-1/3)(x+1/3)
=1/18