因式分解 1) 9(a-b)^2-12(a-b)+4 2) 9-x^2+12xy-36y^2
问题描述：
因式分解 1) 9(a-b)^2-12(a-b)+4 2) 9-x^2+12xy-36y^2
答
1）9(a-b)^2-12(a-b)+4
=[3(a-b)]^2-2*3(a-b)*2+2^2
=[3(a-b)-2]^2
2)9-x^2+12xy-36y^2
=-(x^2-12xy+36y^2-9)
=-[x^2-2*x*6y+(6y)^2-9]
=-[(x-6y)^2-3^2]
=-(x-6y+3)(x-6y-3)
答
1) 9(a-b)^2-12(a-b)+4
=[3(a-b)]²－2×3×2(a-b)＋2²
=[3(a-b)－2]²
=(3a－3b－2)²
2) 9-x^2+12xy-36y^2
=9－(x²－12xy＋36y²)
=3²－(x－6y)²
=(3＋x－6y)(3－x＋6y)