Factor 6x2 plus 11x-10

6x2 + 11x - 10 = (6x2 + 15x) - (4x + 10)

= 3x(2x + 5) - 2(2x + 5)

= (3x - 2)(2x + 5).

Note, first, that the three co-efficients of the original quadratic expression are 6, 11, and -10.

We need two numbers whose sum is 11 and

whose product is (6)(-10) = -60.

These two numbers turn out to be 15 and -4.

Thus, we replace the middle term, 11x with 15x - 4x and proceed with the factorisation in the usual way.