1. **State the problem:** Resolve the following into partial fractions:
$$\frac{x}{x^2+x+4}$$ and $$\frac{x-2}{x^2+4x+4}$$
2. **Recall the formula and rules:**
Partial fraction decomposition is used to express a rational function as a sum of simpler fractions. For quadratic denominators that cannot be factored into real linear factors, the partial fraction form is $$\frac{Ax+B}{quadratic}$$.
3. **First expression:** $$\frac{x}{x^2+x+4}$$
The denominator $$x^2+x+4$$ does not factor nicely (discriminant $$\Delta = 1^2 - 4\times1\times4 = 1-16 = -15 < 0$$), so it is irreducible over the reals.
Thus, the partial fraction form is:
$$\frac{x}{x^2+x+4} = \frac{Ax+B}{x^2+x+4}$$
Multiply both sides by the denominator:
$$x = (Ax+B)$$
Since the denominators are the same, this implies:
$$x = Ax + B$$
Equate coefficients:
Coefficient of $$x$$: $$1 = A$$
Constant term: $$0 = B$$
So, $$A=1$$ and $$B=0$$.
Therefore:
$$\frac{x}{x^2+x+4} = \frac{1\cdot x + 0}{x^2+x+4} = \frac{x}{x^2+x+4}$$
This means the expression is already in simplest partial fraction form.
4. **Second expression:** $$\frac{x-2}{x^2+4x+4}$$
Factor the denominator:
$$x^2+4x+4 = (x+2)^2$$
Since the denominator is a repeated linear factor, the partial fraction decomposition is:
$$\frac{x-2}{(x+2)^2} = \frac{A}{x+2} + \frac{B}{(x+2)^2}$$
Multiply both sides by $$ (x+2)^2 $$:
$$x-2 = A(x+2) + B$$
Expand:
$$x-2 = Ax + 2A + B$$
Equate coefficients:
Coefficient of $$x$$: $$1 = A$$
Constant term: $$-2 = 2A + B$$
Substitute $$A=1$$:
$$-2 = 2(1) + B \Rightarrow B = -2 - 2 = -4$$
Therefore:
$$\frac{x-2}{(x+2)^2} = \frac{1}{x+2} - \frac{4}{(x+2)^2}$$
**Final answers:**
$$\frac{x}{x^2+x+4}$$ (already simplest form)
$$\frac{x-2}{x^2+4x+4} = \frac{1}{x+2} - \frac{4}{(x+2)^2}$$
Partial Fractions Ac4A86
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