Tuesday, August 28, 2012

Reduce to the lowest terms: 3/(x+3) + 2/(3-x) + (2x+24)/(x^2-9).

We notice that the denominator of the 3rd fraction is a
difference of squares that returns the product:


x^2 - 9 =
(x-3)(x+3)


We notice that we can factorize by -1 the
denominator of the 2nd fraction:


2/(3-x) =
-2/(x-3)


We'll re-write the  sum of
fractions:


3/(x+3) - 2/(x-3) + (2x+24)/
(x-3)(x+3)


We'll multiply each fraction by the missing
factor in order to get the LCD (x-3)(x+3)


3(x-3)/(x-3)(x+3)
- 2(x+3)/(x-3)(x+3) + (2x+24)/ (x-3)(x+3)


Since the
fractions have the same denominators, we can re-write the
sum:


[3(x-3) - 2(x+3) + (2x+24)]/
(x-3)(x+3)


(3x - 9 - 2x - 6 + 2x + 24)/
(x-3)(x+3)


We'll combine and eliminate like
terms:


(3x - 9 - 6 + 24)/
(x-3)(x+3)


(3x+9)/
(x-3)(x+3)


We'll factorize the numerator by
3:


3(x+3)/ (x-3)(x+3)


We'll
simplify and we'll
get:


3/(x-3)


The
result of the given sum, reduced to the lowest terms, is
3/(x-3).

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