Solved on Mar 13, 2024

Simplify and express the given rational expression in the form f(x)g(x)\frac{f(x)}{g(x)}.
Problem: Simplify 1x2+3x+21x23x10\frac{1}{x^{2}+3 x+2}-\frac{1}{x^{2}-3 x-10} and give your answers for f(x)f(x) and g(x)g(x).

STEP 1

Assumptions
1. The expression to simplify is 1x2+3x+21x23x10\frac{1}{x^{2}+3x+2}-\frac{1}{x^{2}-3x-10}.
2. We aim to express the simplified form as f(x)g(x)\frac{f(x)}{g(x)}.

STEP 2

Factor the denominators of both fractions to find common factors if any.
The first denominator is x2+3x+2x^{2}+3x+2 and the second is x23x10x^{2}-3x-10.

STEP 3

Factor the first denominator:
x2+3x+2=(x+a)(x+b)x^{2}+3x+2 = (x+a)(x+b)
where aa and bb are numbers that add up to 3 and multiply to 2.

STEP 4

Find the numbers aa and bb for the first denominator:
a=1,b=2a = 1, \quad b = 2
because 1+2=31 + 2 = 3 and 1×2=21 \times 2 = 2.

STEP 5

Write the factored form of the first denominator:
x2+3x+2=(x+1)(x+2)x^{2}+3x+2 = (x+1)(x+2)

STEP 6

Factor the second denominator:
x23x10=(x+c)(x+d)x^{2}-3x-10 = (x+c)(x+d)
where cc and dd are numbers that add up to 3-3 and multiply to 10-10.

STEP 7

Find the numbers cc and dd for the second denominator:
c=5,d=2c = -5, \quad d = 2
because 5+2=3-5 + 2 = -3 and 5×2=10-5 \times 2 = -10.

STEP 8

Write the factored form of the second denominator:
x23x10=(x5)(x+2)x^{2}-3x-10 = (x-5)(x+2)

STEP 9

Rewrite the original expression with the factored denominators:
1(x+1)(x+2)1(x5)(x+2)\frac{1}{(x+1)(x+2)} - \frac{1}{(x-5)(x+2)}

STEP 10

Notice that the denominators have a common factor of (x+2)(x+2). To combine the fractions, we need a common denominator, which will be the product of the distinct factors from both denominators.

STEP 11

Determine the common denominator:
Commondenominator=(x+1)(x+2)(x5)Common\, denominator = (x+1)(x+2)(x-5)

STEP 12

Rewrite both fractions with the common denominator:
1(x5)(x+1)(x+2)(x5)1(x+1)(x+1)(x+2)(x5)\frac{1 \cdot (x-5)}{(x+1)(x+2)(x-5)} - \frac{1 \cdot (x+1)}{(x+1)(x+2)(x-5)}

STEP 13

Combine the numerators over the common denominator:
(x5)(x+1)(x+1)(x+2)(x5)\frac{(x-5) - (x+1)}{(x+1)(x+2)(x-5)}

STEP 14

Expand the numerators and combine like terms:
x5x1(x+1)(x+2)(x5)\frac{x - 5 - x - 1}{(x+1)(x+2)(x-5)}

STEP 15

Simplify the numerator:
6(x+1)(x+2)(x5)\frac{-6}{(x+1)(x+2)(x-5)}

STEP 16

The simplified form of the expression is now:
6(x+1)(x+2)(x5)\frac{-6}{(x+1)(x+2)(x-5)}

STEP 17

Write the final answer in the form f(x)g(x)\frac{f(x)}{g(x)}:
f(x)=6f(x) = -6 g(x)=(x+1)(x+2)(x5)g(x) = (x+1)(x+2)(x-5)
Your answer for the function f(x)f(x) is 6-6. Your answer for the function g(x)g(x) is (x+1)(x+2)(x5)(x+1)(x+2)(x-5).

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