Question

Ryan is trying to determine whether 2.7x – 5.9 is equivalent to 2.8x – 5.9. To test this, he substitutes 0 for x into both expressions. Explain why this will not give him the correct answer.

Answer 1

In order for two expressions to be equivalent, they must be equal for **all** x-values. Therefore, if you simply plug in x = 0 you are only proving, at most, whether they're equal for x = 0.