One waits, the other claims
The board shows n + 3. Below it is n + 3 = 8. Here n is a letter for a number. They look alike. Only one of them can be true or false.
Loading lab…
n + 3 — no equals sign. Step 1 of 3
n + 3— no equals sign.- It waits for a value.
- Add
= 8. Now it claims something.
What each line is for
n + 3 is an expression. Put 5 in place of n, and n + 3 is 8. Put 20 in place of n, and n + 3 is 23. It claims nothing. It does not say that anything is true.
n + 3 = 8 is an equation. It claims that both sides are the same number. So it can be true or false.
Rule: No equals sign means expression. An equals sign with both sides filled means equation.
An equation needs no letter. 9 + 8 = 17 is an equation, and it is true.