因式分解 难难难难1.x^2-x-9y^2-3y2.x^2-y^2-z^2-2yz3.4a^2+9b^2-49c^2-1
4个回答
1.x^2-x-9y^2-3y
=(x+3y)(x-3y)-(x+3y)
=(x+3y)(x-3y-1)
2.x^2-y^2-z^2-2yz
=x^2-(y^2+2yz+z^2)
=x^2-(y+z)^2
=(x+y+z)(x-y-z)
3.4a^2+9b^2-49c^2-12ab
=(2a-3b)^2-49c^2
=(2a-3b+7c)(2a-3b-7c)
4.y(y-2)-(m-1)(m+1)
=y^2-2y-m^2+1
=(y-1)^2-m^2
=(y+m-1)(y-m-1)
5.x^3(x-2y)+y^3(2x-y)
=x^4-2x^3y+2xy^3-y^4
=(x^2+y^2)(x^2-y^2)-2xy(x^2-y^2)
=(x^2-y^2)(x^2+y^2-2xy)
=(x+y)(x-y)^3
6.1+(b-a^2)x^2-abx^3
=1+bx^2-a^2x^2-abx^3
=(1+ax)(1-ax)+bx^2(1-ax)
=(1-ax)(1+ax+bx^2)
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