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16. Simplify:

[tex]\[
\frac{7}{a+8}+\frac{7}{a^2-64}
\][/tex]

A. [tex]\(\frac{14}{(a-8)(a+8)}\)[/tex]

B. [tex]\(\frac{14}{a^2+2-56}\)[/tex]

C. [tex]\(\frac{7a-49}{(a-8)(a+8)}\)[/tex]

D. [tex]\(\frac{7a+63}{(a-8)(a+8)}\)[/tex]


Sagot :

To simplify the given expression:
[tex]\[ \frac{7}{a+8} + \frac{7}{a^2 - 64} \][/tex]

Let's go through the steps:

1. Factor the Denominator:
We notice that [tex]\(a^2 - 64\)[/tex] is a difference of squares, which can be factored as:
[tex]\[ a^2 - 64 = (a - 8)(a + 8) \][/tex]

Therefore, the second fraction becomes:
[tex]\[ \frac{7}{(a - 8)(a + 8)} \][/tex]

2. Combine with a Common Denominator:
The first fraction has [tex]\(a + 8\)[/tex] in the denominator. To combine these two fractions, they should have a common denominator, which is [tex]\((a - 8)(a + 8)\)[/tex]:
[tex]\[ \frac{7}{a + 8} = \frac{7(a - 8)}{(a + 8)(a - 8)} \][/tex]

Now, we can write the original expression as:
[tex]\[ \frac{7(a - 8)}{(a + 8)(a - 8)} + \frac{7}{(a + 8)(a - 8)} \][/tex]

Combine the numerators over the common denominator:
[tex]\[ \frac{7(a - 8) + 7}{(a + 8)(a - 8)} = \frac{7(a - 8) + 7}{a^2 - 64} \][/tex]

3. Simplify the Numerator:
Expand and simplify the numerator:
[tex]\[ 7(a - 8) + 7 = 7a - 56 + 7 = 7a - 49 \][/tex]
So the expression becomes:
[tex]\[ \frac{7a - 49}{a^2 - 64} \][/tex]

4. Check Possible Equivalent Expressions:
Looking at the provided answer options:

[tex]\[ \frac{7}{a+8} + \frac{7}{a^2-64} \][/tex]

We can verify the simplified form is:
[tex]\[ \frac{7a - 49}{(a-8)(a+8)} \][/tex]

Thus, the simplified form of the given expression is:
[tex]\[ \frac{7a - 49}{(a - 8)(a + 8)} \][/tex]