What is the sum?

[tex]\[ \frac{3y}{y^2 + 7y + 10} + \frac{2}{y + 2} \][/tex]

A. \(\frac{5}{y-5}\)

B. \(\frac{5(y+2)}{(y-2)(y+5)}\)

C. \(\frac{5}{y+5}\)

D. [tex]\(\frac{5(y-2)}{(y-5)(y+2)}\)[/tex]



Answer :

To find the sum of the given fractions, we first need to factorize the denominators where possible and then combine the fractions into a single rational expression before simplifying. Let's walk through this step-by-step.

The given expression is:
[tex]\[ \frac{3 y}{y^2+7 y+10}+\frac{2}{y+2} \][/tex]

First, let's factorize the quadratic expression in the denominator \(y^2 + 7y + 10\). We look for two numbers that multiply to 10 (the constant term) and add up to 7 (the coefficient of the linear term \(y\)):

[tex]\[ y^2 + 7y + 10 = (y + 2)(y + 5) \][/tex]

So, the expression now is:
[tex]\[ \frac{3 y}{(y + 2)(y + 5)} + \frac{2}{y + 2} \][/tex]

Next, we need a common denominator to combine these fractions. The least common denominator (LCD) will be \((y + 2)(y + 5)\).

Rewrite each fraction with the common denominator:
[tex]\[ \frac{3 y}{(y + 2)(y + 5)} + \frac{2(y + 5)}{(y + 2)(y + 5)} \][/tex]

Now, combine the numerators over the common denominator:
[tex]\[ \frac{3y + 2(y + 5)}{(y + 2)(y + 5)} \][/tex]

Distribute and simplify the numerator:
[tex]\[ 3y + 2(y + 5) = 3y + 2y + 10 = 5y + 10 \][/tex]

So our fraction becomes:
[tex]\[ \frac{5y + 10}{(y + 2)(y + 5)} \][/tex]

Observe that the numerator \(5y + 10\) can be factored out:
[tex]\[ 5y + 10 = 5(y + 2) \][/tex]

Thus, the fraction simplifies to:
[tex]\[ \frac{5(y + 2)}{(y + 2)(y + 5)} \][/tex]

The \((y + 2)\) terms in the numerator and denominator cancel out:
[tex]\[ \frac{5}{y + 5} \][/tex]

Therefore, the simplified sum of the given fractions is:
[tex]\[ \frac{5}{y + 5} \][/tex]

The correct answer is:
[tex]\[ \boxed{\frac{5}{y+5}} \][/tex]