Please help Factorise fully 1. X^2-5x-14 2. Ab^2+3b 3. A^3-8a^2+15a

Answer 1

14 = 7*2 always :)

(x-7)(x+2)

------------------
b(Ab+3)
-----------------
suspect you mean
a^3-8a^2+15a
which is
a (a^2-8a+15)
but we know 15 = 3 * 5 and 3+5=8 :)
so
a (a-5)(a-3)