<PRE><B>Question 259048</B>
A variable is just any letter of the alphabet that stands for some unknown amount. X and Y are the most common variables.

EX: X
--
A variable expression is numbers, letters, +,-, x, /, signs, but NO EQUAL sign.
EX: 2x^2 - 3x + 43
--
An equation contains an equal sign somewhere
EX: 5 + x = 10
EX: x^2 + 2x + 4 = 0
EX: 2x^2 + 5y^2 = 1</PRE>