因式分解:3x2+4xy-y2.

问题描述:

因式分解:3x2+4xy-y2

3x2+4xy-y2
=3(x2+

4
3
xy-
1
3
y2
=3[(x2+2×
2
3
xy+
4
9
y2)-
1
3
y2-
4
9
y2]
=3[(x+
2
3
y)2-
7
9
y2]
=3(x+
2
3
y+
7
3
y)(x+
2
3
y-
7
3
y)
=3[x+
2+
7
3
y)(x-
2−
7
3
y).