①2x^2+xy-y^2-4x+5y-6 ②x^2+4xy-4y^2,我算出来=﹙x+2y+2√2·y﹚﹙x+2y-2√2·y﹚③x^2+2x-1=(x+1+√2)(x+1-√2)对不对?
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①2x^2+xy-y^2-4x+5y-6 ②x^2+4xy-4y^2,我算出来=﹙x+2y+2√2·y﹚﹙x+2y-2√2·y﹚③x^2+2x-1=(x+1+√2)(x+1-√2)对不对?
①2x^2+xy-y^2-4x+5y-6
②x^2+4xy-4y^2,我算出来=﹙x+2y+2√2·y﹚﹙x+2y-2√2·y﹚
③x^2+2x-1=(x+1+√2)(x+1-√2)对不对?
①2x^2+xy-y^2-4x+5y-6 ②x^2+4xy-4y^2,我算出来=﹙x+2y+2√2·y﹚﹙x+2y-2√2·y﹚③x^2+2x-1=(x+1+√2)(x+1-√2)对不对?
2x^2+xy-y^2-4x+5y-6
=(2x-y)(x+y)-4x+5y-6
=(2x-y)(x+y)+(2x+2y)-6x+3y-6
=(2x-y)(x+y)+2(x+y)-6x+3y-6
=(x+y)(2x-y+2)-3(2x-y+2)
=(x+y-3)(2x-y+2)
对的
x^2+4xy-4y^2
=x^2+4xy+4y^2-8y^2
=(X+2Y)^2-8y^2
=(X+2Y-2√2Y)(X+2Y+2√2Y)
对的
x^2+2x-1
=x^2+2x+1-2
=(x+1)^2-(√2)^2
=(x+1-√2)(x+1+√2)
1 =(2x-y+2)(x+y-3)。先分解前面的二次项,这个十字交叉法很容易。然后再凑后面,稍微凑一凑就出来了
2你算的是对的
3 也是对的
①2x^2+xy-y^2-4x+5y-6
=(2x-y)(x+y)-4x+5y-6
=(2x-y+2)(x+y-3)
②x^2+4xy-4y^2=﹙x+2y+2√2·y﹚﹙x+2y-2√2·y﹚对
③x^2+2x-1=(x+1+√2)(x+1-√2)对