Skip to main content
### Number and algebra

### Geometry and measure

### Probability and statistics

### Working mathematically

### Advanced mathematics

### For younger learners

# Implicitly

Use the quadratic equation formula. When are the roots real?

Note that $X(r)$ is a 'multivalued' function with $2$ possible values of $X$ for each value of $r$.

## You may also like

Or search by topic

Age 16 to 18

Challenge Level

- Problem
- Getting Started
- Student Solutions
- Teachers' Resources

Use the quadratic equation formula. When are the roots real?

Note that $X(r)$ is a 'multivalued' function with $2$ possible values of $X$ for each value of $r$.