Decomposition factor: quadratic form of (1)a+quadratic form of14ab+45b (2) quadratic form of a-quadratic form of -9ab+20b. Decomposition factor: quadratic of a-quadratic of 5a +4. Decomposition factor: 2a+4+3ab+6b 17. x2(x—y)—3xy(y—x) 19、a4—2a2b2+b4 20、—4b2 2 1、9(m+2n)2—4(m—n)2 22、ab—a—b+ 1 23、4x2—4xy+y2 24、x2y—4y3 25 、( b+c)m+(c+a)m+(a+b)m 26、4(p—