Subtract. Enter your answer as a single rational expression where the numerator and denominator have no common factors.

[tex]\[ \frac{3m - 18}{m^2 - 10m + 24} - \frac{m + 8}{4 - m} \][/tex]



Answer :

Certainly! Let's go through the steps to subtract the given rational expressions and simplify the result.

We start with the following expressions:
[tex]\[ \frac{3m - 18}{m^2 - 10m + 24} - \frac{m + 8}{4 - m} \][/tex]

Step 1: Simplify the second fraction, if possible

Notice that the denominator [tex]\(4 - m\)[/tex] can be written as [tex]\( -(m - 4)\)[/tex]. Thus, the second fraction becomes:
[tex]\[ \frac{m + 8}{4 - m} = \frac{m + 8}{-(m - 4)} = -\frac{m + 8}{m - 4} \][/tex]

Now, our expression looks like this:
[tex]\[ \frac{3m - 18}{m^2 - 10m + 24} - \left( -\frac{m + 8}{m - 4} \right) \][/tex]

Which simplifies to:
[tex]\[ \frac{3m - 18}{m^2 - 10m + 24} + \frac{m + 8}{m - 4} \][/tex]

Step 2: Factor the denominators, if necessary (factoring the quadratic expression)

The denominator [tex]\(m^2 - 10m + 24\)[/tex] can be factored by looking for factors of 24 that sum up to -10. The correct factors are -6 and -4:
[tex]\[ m^2 - 10m + 24 = (m - 6)(m - 4) \][/tex]

So, our expression is now:
[tex]\[ \frac{3m - 18}{(m - 6)(m - 4)} + \frac{m + 8}{m - 4} \][/tex]

Step 3: Combine the fractions by finding a common denominator

The common denominator in this case is [tex]\((m - 6)(m - 4)\)[/tex]. We need to express [tex]\(\frac{m + 8}{m - 4}\)[/tex] with this common denominator:
[tex]\[ \frac{m + 8}{m - 4} = \frac{(m + 8)(m - 6)}{(m - 6)(m - 4)} \][/tex]

So, now we have:
[tex]\[ \frac{3m - 18}{(m - 6)(m - 4)} + \frac{(m + 8)(m - 6)}{(m - 6)(m - 4)} \][/tex]

Step 4: Add the numerators over the common denominator

The numerators are [tex]\(3m - 18\)[/tex] and [tex]\((m + 8)(m - 6)\)[/tex]. First, expand [tex]\((m + 8)(m - 6)\)[/tex]:
[tex]\[ (m + 8)(m - 6) = m^2 - 6m + 8m - 48 = m^2 + 2m - 48 \][/tex]

Now add the numerators:
[tex]\[ \frac{3m - 18 + (m^2 + 2m - 48)}{(m - 6)(m - 4)} = \frac{m^2 + 2m - 48 + 3m - 18}{(m - 6)(m - 4)} = \frac{m^2 + 5m - 66}{(m - 6)(m - 4)} \][/tex]

Step 5: Simplify the resulting expression if possible

To ensure the simplified expression has no common factors in the numerator and denominator, check if the numerator [tex]\(m^2 + 5m - 66\)[/tex] factors further.

It does not factor any further in a real number field, so the rational expression is completely simplified.

Final Answer:
[tex]\[ \frac{m^2 + 5m - 66}{(m - 6)(m - 4)} \][/tex]

This can be further verified to simplify to [tex]\(\frac{m + 11}{m - 4}\)[/tex] upon performing polynomial long division.

Hence, the final simplified form is:
[tex]\[ \boxed{\frac{m + 11}{m - 4}} \][/tex]

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