You're going to need to show us the rest of the question for us to do (iii)
C.
$A double root at $ x = 1 $ means $ p(1) = 0 $ and $ p'(1) = 0
p(x) = 2x^3 - (2a + 1)x^2 + (2 + b)x - 1 \\\\ p'(x) = 6x^2 -2(2a+1)x + (2+b) \\\\ p'(1) = 6 - 4a - 2 + 2 + b = 0 \\\\ 6 - 4a + b = 0 \\\\ p(1) = 2 - 2a...