given that 6x^3+5a-12a leaves a remainder of -4 when divided by (x-a). what will be the possible value of a ?

Answer 1

Assuming a typo, we have
f(a) = 6a^3+5a^2-12a = -4
6a^3+5a^2-12a+4 = 0
(a+2)(2a-1)(3a-2) = 0
. . .