# What is the complex conjugate of 2 + i?

$2 - i$
Just like the conjugate of $2 + x$ is $2 - x$, the complex conjugate of $2 + i$ is $2 - i$.
To generalize the rule, the complex conjugate of $a + b i$ is $a - b i$ —the constant stays the same, and it's added to the opposite of the complex number. Super simple!