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Select the correct answer.

Assuming that no denominator equals zero, what is the simplest form of this expression?

[tex]\[
\frac{x+2}{x^2+5x+6} \div \frac{3x+1}{x^2-9}
\][/tex]

A. [tex]\(\frac{1}{(x+3)(x-3)}\)[/tex]

B. [tex]\(\frac{x-3}{3x+1}\)[/tex]

C. [tex]\(\frac{3x+1}{x-3}\)[/tex]

D. [tex]\(\frac{1}{3x+1}\)[/tex]


Sagot :

To simplify the given expression:
[tex]\[ \frac{x+2}{x^2 + 5x + 6} \div \frac{3x+1}{x^2 - 9} \][/tex]

Follow these steps:

1. Rewrite the division as multiplication by the reciprocal:
[tex]\[ \frac{x+2}{x^2 + 5x + 6} \times \frac{x^2 - 9}{3x+1} \][/tex]

2. Factorize the denominators and numerators if possible:
- [tex]\( x^2 + 5x + 6 \)[/tex] can be factorized as [tex]\( (x + 2)(x + 3) \)[/tex].
- [tex]\( x^2 - 9 \)[/tex] is a difference of squares and can be factorized as [tex]\( (x + 3)(x - 3) \)[/tex].

Thus, the expression becomes:
[tex]\[ \frac{x+2}{(x + 2)(x + 3)} \times \frac{(x + 3)(x - 3)}{3x+1} \][/tex]

3. Cancel out the common terms in the numerator and the denominator:
- The [tex]\( x + 2 \)[/tex] terms cancel out.
- The [tex]\( x + 3 \)[/tex] terms cancel out.

This simplifies to:
[tex]\[ \frac{1}{x + 3} \times \frac{x - 3}{3x + 1} = \frac{x - 3}{3x + 1} \][/tex]

So, the simplest form of the given expression is:
[tex]\[ \frac{x - 3}{3x + 1} \][/tex]

Hence, the correct answer is:
B. [tex]\(\frac{x-3}{3 x+1}\)[/tex]