c = 5
using the Remainder Theorem.
If a polynomial f(x) is divided by (x - a) then remainder is f(a)
for (x - 2 ) → a = 2
evaluating the polynomial f(2) gives
f(2) = 2(2)³ -c(2)² +4(2) - 7 = - 3 = 16 -4c + 8 - 7 = -3 → ( solve for c )
17 - 4c = - 3 → - 4c = - 3 - 17 = - 20 ⇒ c = 5
f(x) = 2x³ -5x² + 4x - 7
