Multiply.

Enter your answer as a single, completely simplified rational expression with nonnegative exponents.

[tex]\[ \frac{6 m^2}{m^2+13 m+36} \cdot \frac{m^2-16}{18 m} \][/tex]



Answer :

Let's multiply the given rational expressions and simplify the result step by step.

The given expressions are:
[tex]\[ \frac{6 m^2}{m^2 + 13 m + 36} \cdot \frac{m^2 - 16}{18 m} \][/tex]

### Step 1: Factor the polynomials

First, we need to factor the quadratic expressions in the numerators and denominators wherever possible.

1. The denominator [tex]\( m^2 + 13 m + 36 \)[/tex]:
[tex]\[ m^2 + 13 m + 36 = (m + 4)(m + 9) \][/tex]

2. The numerator [tex]\( m^2 - 16 \)[/tex]:
[tex]\[ m^2 - 16 = (m - 4)(m + 4) \][/tex]
(This is the difference of squares.)

### Step 2: Rewrite the expressions with the factored forms

Now we rewrite the original problem using these factored forms:
[tex]\[ \frac{6 m^2}{(m + 4)(m + 9)} \cdot \frac{(m - 4)(m + 4)}{18 m} \][/tex]

### Step 3: Multiply the fractions

To multiply the fractions, we multiply the numerators together and the denominators together:
[tex]\[ \frac{6 m^2 (m - 4)(m + 4)}{(m + 4)(m + 9) \cdot 18 m} \][/tex]

### Step 4: Simplify the expression

Now, we look for common factors in the numerator and denominator that can be cancelled out to simplify the expression:
- The factor [tex]\(m + 4\)[/tex] appears in both the numerator and the denominator.
- The factor [tex]\(m\)[/tex] appears in both the numerator ([tex]\(6 m^2\)[/tex]) and the denominator ([tex]\(18 m\)[/tex]).

After cancelling the common factors:
[tex]\[ \frac{6 m (m - 4) \cancel{(m + 4)}}{\cancel{(m + 4)} 18 (m + 9)} \][/tex]

Divide [tex]\(6 m\)[/tex] by [tex]\(18\)[/tex]:
[tex]\[ \frac{m (m - 4)}{3 (m + 9)} \][/tex]

This can be simplified further:
[tex]\[ \frac{m^2 - 4m}{3 (m + 9)} \][/tex]

The simplified expression is:
[tex]\[ \boxed{\frac{m^2 - 4m}{3 (m + 9)}} \][/tex]

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