If the points P (a + B, - 5) and (1, 3a-b) are symmetric with respect to the origin, then the quadratic trinomial x2-2ax-b2 with respect to X can be decomposed into______ ．

If the points P (a + B, - 5) and (1, 3a-b) are symmetric with respect to the origin, then the quadratic trinomial x2-2ax-b2 with respect to X can be decomposed into______ ．

According to "the abscissa and ordinate of the point symmetrical about the origin are opposite to each other", a + B = - 1, 3a-b = 5, the solution is a = 1, B = - 2, so x2-2ax-b2 = x2-2x + 1 = (x-1) 2

Decompose the following factors 1 x ^ 2 + 7x-82.3a ^ 2-7a-6 by cross multiplication
3.3x^2-8x-3
4.5x^2+12-9

1.3x^2-8x-3=(3x+1)(x-3)
2.5x^2+12x-9=（5x-3)(x+3)

Cross phase multiplication factorization factor 2A ^ 2-7a + 6

1 -2
2 -3
(A-2)(2a-3)