The conjugate is where we change the sign in the middle of two terms like this:
We only use it in expressions with two terms, called “binomials”:
 |
| (example of a binomial) |
Here are some more examples:
| Expression | Its Conjugate | |
|---|---|---|
| x2 − 3 | ⇒ | x2 + 3 |
| a + b | ⇒ | a − b |
| a − b3 | ⇒ | a + b3 |
Examples of Use
The conjugate can be very useful because …
… when we multiply something by its conjugate we get squares like this:
How does that help?
It can help us move a square root from the bottom of a fraction (the denominator) to the top, or vice versa.
