13
(x+13)(x+4)
(6x + 1)(x + 13)
-x2 + 11x + 26 = -(x - 13)(x + 2) = (13 - x)(x + 2) = (x - 13)(-x - 2)
3 squared plus 2 squared is equal to 13.
There is no rational factorisation of 6y2 + 19y - 13 The roots are [-19 +/- sqrt(673)]/12 which are -3.74519 and 0.57852
9 plus 2 squared is equal to 13.
The factors of that trinomial are (x - 13) and (x + 3) . Neither of them appears below.
13
-(x + 2)(x - 13)
2 (squared), 3 and 13.
4