Question 435546
15a^2-65a-50
=5(3a^2-13a-10)
3*-10=-30. the two factors of -30 whose sum is -13 are +2 and -15.
=5(3a^2+2a-15a-10)
=5(a(3a+2)-5(3a+2)) Factoring by grouping.
=5(a-5)(3a+2)
.
Ed