因式分解:3x2+5xy-2y2+x+9y-4 x2+x-(a2-a) 3x2+4xy-y2 x,y,a后面的2表示平方
3个回答
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3x^2+5xy-2y^2+x+9y-4
=(x+2y)(3x-y)+x+9y-4
=(x+2y)(3x-y)+4(x+2y)-(3x-y)-4
=(x+2y-1)(3x-y+4)
x^2+x-(a^2-a)
=(x^2-a^2)+x+a
=(x+a)(x-a)+(x+a)
=(x+a)(x-a+1)
3x^2+4xy-y^2
= 3(x^2+ xy*4/3 - y^2*1/3)
= 3[(x^2+ 2*2/3 *xy +4/9y^2) - y^2/3- 4/9y^2]
= 3[(x+2/3y)^2 - 7/9 y^2]
=3(x+2/3y +√7/3y)(x+2/3y - √7/3y)
= 3[x+(2+√7)/3y][x+(2-√7)/3y]
=(x+2y)(3x-y)+x+9y-4
=(x+2y)(3x-y)+4(x+2y)-(3x-y)-4
=(x+2y-1)(3x-y+4)
x^2+x-(a^2-a)
=(x^2-a^2)+x+a
=(x+a)(x-a)+(x+a)
=(x+a)(x-a+1)
3x^2+4xy-y^2
= 3(x^2+ xy*4/3 - y^2*1/3)
= 3[(x^2+ 2*2/3 *xy +4/9y^2) - y^2/3- 4/9y^2]
= 3[(x+2/3y)^2 - 7/9 y^2]
=3(x+2/3y +√7/3y)(x+2/3y - √7/3y)
= 3[x+(2+√7)/3y][x+(2-√7)/3y]
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3x^2+5xy-2y^2+x+9y-4
=(x+2y)(3x-y)+4(x+2y)-(3x-y)-4
=(x+2y-1)(3x-y+4)
x^2+x-(a^2-a)
=x^2-a^2+x+a
=(x+a)(x-a)+(x+a)
=(x+a)(x-a+1)
3x^2+4xy-y^2
=3(x+2y/3)^2-7y^2/3
=(1/3)[3x+(2+√7)y][3x+(2-√7)y]
=(x+2y)(3x-y)+4(x+2y)-(3x-y)-4
=(x+2y-1)(3x-y+4)
x^2+x-(a^2-a)
=x^2-a^2+x+a
=(x+a)(x-a)+(x+a)
=(x+a)(x-a+1)
3x^2+4xy-y^2
=3(x+2y/3)^2-7y^2/3
=(1/3)[3x+(2+√7)y][3x+(2-√7)y]
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你这里应该是3道题吧。希望下次写清楚。
1.3x2+5xy-2y2+x+9y-4
=(3x-y)(x+2y)+x+9y-4
=(3x-y)(x+2y)-(3x-y)+4x+8y-4
=(3x-y)(x+2y-1)+4(x+2y-1)
=(3x-y+4)(x+2y-1)
2.x2+x-(a2-a)
=x2+x-a(a-1)
=(x+a)(x-a+1)
3.3x2+4xy-4y2
=(3x-2)(x+2)
1.3x2+5xy-2y2+x+9y-4
=(3x-y)(x+2y)+x+9y-4
=(3x-y)(x+2y)-(3x-y)+4x+8y-4
=(3x-y)(x+2y-1)+4(x+2y-1)
=(3x-y+4)(x+2y-1)
2.x2+x-(a2-a)
=x2+x-a(a-1)
=(x+a)(x-a+1)
3.3x2+4xy-4y2
=(3x-2)(x+2)
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