Find the remainder when f(x) = 2x^3 − x^2 + x + 1 is divided by 2x + 1.
The remainder theorem states that f(x) / (x - a) will have a remainder of f(a).
However, this doesn't apply if the coefficient of the x-term isn't 1.
So first, let's divide both f(x) and 2x + 1 by 2:
--- This is legal because f(x) / (x - a) = [ f(x) / 2 ] / [ (x - a) / 2) ].
f(x) / 2 = (2x^3 − x^2 + x + 1) / 2 = x^3 − (1/2)x^2 + (1/2)x + (1/2)
(2x + 1) / 2 = x + (1/2)
Now, the coefficient of the x-term is 1.
So, to find the remainder when x^3 − (1/2)x^2 + (1/2)x + (1/2) is divided by x + (1/2), replace x with -(1/2):
---> (-1/2)^3 − (1/2)(-1/2)^2 + (1/2)(-1/2) + (1/2)
---> -1/8 - 1/8 - 1/4 + 12
---> -1/8 - 1/8 - 2/8 + 4/8
---> 0
Therefore, the remainder will be 0.