Conjugate
The conjugate is where we change the sign in the middle of two terms like this:
conjugate of 3x+1 is 3x-1
We only use it in expressions with two terms, called "binomials":
Binomial
Here are some more examples:
Expression Its Conjugate
x2 − 3 ⇒ x2 + 3
a + b ⇒ a − b
a − b3 ⇒ a + b3