Solving -3x = 18

Pre-Algebra · Axiom Academy

Identify the operation on the variable, then apply its inverse — dividing by a negative — to solve an equation with a negative coefficient. Solve the equation -3x = 18 for x . We need to get x by itself on one side of the equation. Nice work — you solved an equation with a negative coefficient. Keep these steps in mind: Identify the operation: figure out what's being done to the variable — here, x was multiplied by -3 . Use the inverse operation: the inverse of multiplication is division, so we divided both sides by -3 . Divide by negatives carefully: a negative divided by a negative is positive, so , while . Keep the equation balanced: whatever you do to one side, do to the other. Always check: substitute the answer back in — -3(-6) = 18 confirms x = -6 . The same process solves any one-step equation: identify the operation, apply its inverse to both sides, simplify, and check your work.

This is the written version of the interactive lesson above. See the full Pre-Algebra course.