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Find the limit, if it exists.

[tex]\[ \lim _{x \rightarrow 3}\left(\frac{x^2-9}{x-3}+\sqrt{x^2+7}\right) \][/tex]


Sagot :

To find the limit [tex]\(\lim _{x \rightarrow 3}\left(\frac{x^2-9}{x-3} + \sqrt{x^2+7}\right)\)[/tex], let's break it down step by step.

First, we look at the expression inside the limit:

[tex]\[ \frac{x^2 - 9}{x - 3} + \sqrt{x^2 + 7} \][/tex]

### Step 1: Simplify the Rational Function [tex]\(\frac{x^2 - 9}{x - 3}\)[/tex]

The term [tex]\(\frac{x^2 - 9}{x - 3}\)[/tex] can be simplified. Notice that [tex]\(x^2 - 9\)[/tex] can be factored as a difference of squares:

[tex]\[ x^2 - 9 = (x - 3)(x + 3) \][/tex]

Thus,

[tex]\[ \frac{x^2 - 9}{x - 3} = \frac{(x - 3)(x + 3)}{x - 3} \][/tex]

For [tex]\(x \neq 3\)[/tex], the term [tex]\((x - 3)\)[/tex] in the numerator and denominator cancels out:

[tex]\[ \frac{(x - 3)(x + 3)}{x - 3} = x + 3 \][/tex]

### Step 2: Substitute the Simplified Expression Back

Now the expression becomes:

[tex]\[ x + 3 + \sqrt{x^2 + 7} \][/tex]

### Step 3: Evaluate the Limit

Now, we need to evaluate the limit of this simplified expression as [tex]\(x\)[/tex] approaches 3:

[tex]\[ \lim_{x \to 3} \left(x + 3 + \sqrt{x^2 + 7}\right) \][/tex]

Substitute [tex]\(x = 3\)[/tex]:

[tex]\[ 3 + 3 + \sqrt{3^2 + 7} \][/tex]

Simplify inside the square root:

[tex]\[ 3 + 3 + \sqrt{9 + 7} = 3 + 3 + \sqrt{16} = 3 + 3 + 4 = 10 \][/tex]

### Conclusion

Therefore,

[tex]\[ \lim _{x \rightarrow 3}\left(\frac{x^2-9}{x-3} + \sqrt{x^2+7}\right) = 10 \][/tex]