Problem

Question 2 For a certain polynomial $P(x), P(3)=2$ and $P(-1)=-1$. Use this information to deduce the remainder when $P(x)$ is divided by $(x-3)(x+1)$.

Solution

Step 1 :By the Remainder Theorem, we have $P(3) = 2$ and $P(-1) = -1$.

Step 2 :Let $Q(x)$ and $ax + b$ be the quotient and remainder, respectively, when the polynomial $P(x)$ is divided by $(x - 3)(x + 1)$, so $P(x) = (x - 3)(x + 1) Q(x) + ax + b$.

Step 3 :Setting $x = 3$, we get $P(3) = 3a + b$, so $3a + b = 2$.

Step 4 :Setting $x = -1$, we get $P(-1) = -a + b$, so $-a + b = -1$.

Step 5 :Solving the system of equations, we find $a = 1$ and $b = -3$.

Step 6 :Therefore, the remainder is \(\boxed{x - 3}\).

From Solvely APP
Source: https://solvelyapp.com/problems/26044/

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