when P(x) is divided by (x+1), the remainder is 3. What is the remainder when xP(x) is divided by (x+1)?

When Q(x) be the quotient when P(x) is divided by (x + 1).
Then P(x) = (x + 1)•Q(x) + 3

Let f(x) = xP(x)
Then, f(x) = x[(x + 1)•Q(x) + 3]
f(x) = x(x + 1)•Q(x) + 3x

When f(x) is divided by (x + 1), the remainder
= f(-1)
= 0 + 3(-1)
= -3