Question

If f(x) = 2x6 + 3x5 – 1, then what is the remainder when f(x) is divided by x + 1?

Answer 1

Answer:   -2

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Explanation:

We use the remainder theorem. This is the idea where if we divide P(x) over (x-k), then the remainder is P(k).

Comparing x+1 to x-k shows that k = -1

It might help to rewrite x+1 as x-(-1) to get it into the form x-k better.

Plug this k value into the function

f(x) = 2x^6 + 3x^5 - 1

f(-1) = 2(-1)^2 + 3(-1)^5 - 1

f(-1) = 2(1) + 3(-1) - 1

f(-1) = 2 - 3 - 1

f(-1) = -1 - 1

f(-1) =-2

The remainder is -2

We can confirm this through synthetic division or polynomial long division.