Find Where Undefined/Discontinuous (21y)/(5y-7)

$\frac{21 y}{5 y - 7}$

Step 1

Set the denominator in $\frac{21 y}{5 y - 7}$ equal to $0$ to find where the expression is undefined.

$5 y - 7 = 0$

Step 2

Solve for $y$ .

Add $7$ to both sides of the equation.

$5 y = 7$

Divide each term in $5 y = 7$ by $5$ and simplify.

Divide each term in $5 y = 7$ by $5$ .

$\frac{5 y}{5} = \frac{7}{5}$

Simplify the left side.

Cancel the common factor of $5$ .

Cancel the common factor.

$\frac{5 y}{5} = \frac{7}{5}$

Divide $y$ by $1$ .

$y = \frac{7}{5}$

Step 3