Question

P(2) = 8a-b = 0 simply

Answer 1

P(x) => ax^4 + 2x^3 - 3x^2 +bx - 4 = 0
then
P(2) => 16a + 16 - 12 +2b - 4 = 0 ( putting X = 2)
=> 8a - b =0