有公因式先提公因式
记住平方公式+平方差公式
4a^2b-a^2b^3
=a^2b(4-b^2)
=a^2b(2^2-b^2)
=a^2b(2-b)(2+b)
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3x^2-3=3(x^2-1)=3(x-1)(x+1)
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x^3y^2-4x
=x(x^2y^2-4)
=x[(xy)^2-2^2]
=x(xy-2)(xy+2)
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27x^2-18x+3
=3(9x^2-6x+1)
=3[(3x)^2-2*3x*1+1^2]
=3(3x-1)^2
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25a^2-10(a-b)+1题目不对吧?
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1/2x^2+xy+1/2y^2
=(1/2)[x^2+2xy+y^2]
=(1/2)(x+y)^2
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-x3y+xy^3=xy(y^2-x^2)=xy(y-x)(y+x)
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-3x^7+24x^5-48x^3
=-3x^3(x^4-8x^2+16)
把x^2看成未知数
=-3x^3(x^2-4)^2
=-3x^3(x-2)^2(x+2)^2
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(a+b)^2-4(a+b-1)
=(a+b)^2-4(a+b)+4
=(a+b-2)^2
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4x^2-25
=(2x)^2-5^2
=(2x-5)(2x+5)