因式分解 1) 9(a-b)^2-12(a-b)+4 2) 9-x^2+12xy-36y^2

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因式分解 1) 9(a-b)^2-12(a-b)+4 2) 9-x^2+12xy-36y^2
因式分解 1) 9(a-b)^2-12(a-b)+4 2) 9-x^2+12xy-36y^2

因式分解 1) 9(a-b)^2-12(a-b)+4 2) 9-x^2+12xy-36y^2
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)


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)