The sum of a number and its additive inverse is 0.
-5x
Practice makes perfect
The sum of a number and its additive inverse is 0. We can find the additive inverse by changing the sign of the given number.
a + ( - a)=0
We can follow this line of thinking with the given number.
5x + ( -5x)=0
The additive inverse of 5x is -5x.