Partial Fraction 97000C
1. **State the problem:** Find the partial fraction decomposition of the rational expression $$\frac{10}{5x^2 - 11x + 2}$$.
2. **Factor the denominator:** We need to factor the quadratic polynomial in the denominator.
$$5x^2 - 11x + 2$$
We look for two numbers that multiply to $$5 \times 2 = 10$$ and add to $$-11$$. These numbers are $$-10$$ and $$-1$$.
Rewrite the middle term:
$$5x^2 - 10x - x + 2$$
Group terms:
$$5x(x - 2) - 1(x - 2)$$
Factor out the common binomial:
$$(5x - 1)(x - 2)$$
3. **Set up the partial fractions:** Since the denominator factors as $$(5x - 1)(x - 2)$$, the decomposition is:
$$\frac{10}{(5x - 1)(x - 2)} = \frac{A}{5x - 1} + \frac{B}{x - 2}$$
where $$A$$ and $$B$$ are constants to be determined.
4. **Multiply both sides by the denominator to clear fractions:**
$$10 = A(x - 2) + B(5x - 1)$$
5. **Expand the right side:**
$$10 = A x - 2A + 5 B x - B$$
Group like terms:
$$10 = (A + 5B) x + (-2A - B)$$
6. **Equate coefficients of like terms:**
For $$x$$ term:
$$A + 5B = 0$$
For constant term:
$$-2A - B = 10$$
7. **Solve the system of equations:**
From $$A + 5B = 0$$, we get $$A = -5B$$.
Substitute into the second equation:
$$-2(-5B) - B = 10$$
$$10B - B = 10$$
$$9B = 10$$
$$B = \frac{10}{9}$$
Then,
$$A = -5 \times \frac{10}{9} = -\frac{50}{9}$$
8. **Write the final partial fraction decomposition:**
$$\frac{10}{5x^2 - 11x + 2} = \frac{-\frac{50}{9}}{5x - 1} + \frac{\frac{10}{9}}{x - 2} = -\frac{50}{9(5x - 1)} + \frac{10}{9(x - 2)}$$
This is the partial fraction decomposition with integer and fractional coefficients as required.