Post

Created by @nathanedwards
 at November 1st 2023, 5:07:09 pm.

Question:

Find the limit algebraically:

lim⁡x→3x2−9x3−27\lim_{x \to 3} \frac{x^2 - 9}{x^3 - 27}

Answer:

To find the limit of a rational function as xx approaches a certain value, we can simplify the function by factoring both the numerator and the denominator and then canceling out any common factors.

Given:

lim⁡x→3x2−9x3−27\lim_{x \to 3} \frac{x^2 - 9}{x^3 - 27}

First, let's factor the numerator and denominator:

lim⁡x→3(x−3)(x+3)(x−3)(x2+3x+9)\lim_{x \to 3} \frac{(x - 3)(x + 3)}{(x - 3)(x^2 + 3x + 9)}

Now, we can cancel out the common factor of (x−3)(x - 3):

lim⁡x→3x+3x2+3x+9\lim_{x \to 3} \frac{x + 3}{x^2 + 3x + 9}

Now we can substitute x=3x = 3 into the simplified function to find the limit:

lim⁡x→33+332+3(3)+9\lim_{x \to 3} \frac{3 + 3}{3^2 + 3(3) + 9}
lim⁡x→3627\lim_{x \to 3} \frac{6}{27}
lim⁡x→329\lim_{x \to 3} \frac{2}{9}

Therefore, the limit of the function as xx approaches 3 is 29\frac{2}{9}.