Definition
One-step equation
A one-step equation can be solved by one inverse operation that isolates the unknown.
What it means
An equation is balanced: both sides have the same value. Undo the one operation attached to the unknown, and do the same thing to both sides so the balance stays true.
Remember it
Undo once, on both sides.
Example
Solve x + 7 = 12. Subtract 7 from both sides: x + 7 − 7 = 12 − 7, so x = 5. Check: 5 + 7 = 12.
Watch for
The equation 2x + 3 = 11 needs subtraction and division, so it is a two-step equation.
Common mix-up
Changing only one side breaks the equality. Whatever operation you use must be applied to both sides.
Exact meaning
A one-step equation is an equation in which one inverse operation, applied to both sides, is enough to leave the unknown alone and find its value.