Find Where Undefined/Discontinuous (3x^2-9x)/(5x-15)

$\frac{3 x^{2} - 9 x}{5 x - 15}$

Step 1

Set the denominator in $\frac{3 x^{2} - 9 x}{5 x - 15}$ equal to $0$ to find where the expression is undefined.

$5 x - 15 = 0$

Step 2

Solve for $x$ .

Add $15$ to both sides of the equation.

$5 x = 15$

Divide each term in $5 x = 15$ by $5$ and simplify.

Divide each term in $5 x = 15$ by $5$ .

$\frac{5 x}{5} = \frac{15}{5}$

Simplify the left side.

Cancel the common factor of $5$ .

Cancel the common factor.

$\frac{5 x}{5} = \frac{15}{5}$

Divide $x$ by $1$ .

$x = \frac{15}{5}$

Simplify the right side.

Divide $15$ by $5$ .

$x = 3$

Step 3