1. **State the problem:** We are given a polynomial $$P(x) = x^5 + x^2 + ax + b$$ and it is divided by $$x^2 - 1$$. The remainder is $$2x + 3$$. We need to find the values of $$a$$ and $$b$$.
2. **Recall the Remainder Theorem for quadratic divisors:** When a polynomial $$P(x)$$ is divided by a quadratic polynomial $$D(x)$$, the remainder $$R(x)$$ is a polynomial of degree less than 2. Here, $$R(x) = 2x + 3$$.
3. Since $$x^2 - 1 = (x-1)(x+1)$$, the remainder satisfies:
$$P(1) = R(1)$$ and $$P(-1) = R(-1)$$.
4. Calculate $$P(1)$$:
$$P(1) = 1^5 + 1^2 + a(1) + b = 1 + 1 + a + b = 2 + a + b$$
Calculate $$R(1)$$:
$$R(1) = 2(1) + 3 = 5$$
Set equal:
$$2 + a + b = 5$$
5. Calculate $$P(-1)$$:
$$P(-1) = (-1)^5 + (-1)^2 + a(-1) + b = -1 + 1 - a + b = 0 - a + b = -a + b$$
Calculate $$R(-1)$$:
$$R(-1) = 2(-1) + 3 = -2 + 3 = 1$$
Set equal:
$$-a + b = 1$$
6. Solve the system of equations:
$$\begin{cases} 2 + a + b = 5 \\ -a + b = 1 \end{cases}$$
From the first equation:
$$a + b = 3$$
From the second equation:
$$-a + b = 1$$
Add both equations:
$$ (a + b) + (-a + b) = 3 + 1 $$
$$ \cancel{a} + b - \cancel{a} + b = 4 $$
$$ 2b = 4 $$
$$ b = 2 $$
Substitute $$b=2$$ into $$a + b = 3$$:
$$ a + 2 = 3 $$
$$ a = 1 $$
**Final answer:** $$a = 1$$ and $$b = 2$$.
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