What are linear equations?

Linear equations are equation that, when graphed, produce a straight line.

Their equations can look like:

   x = a  --->  examples:  x = -12  or  x = 0  or  x = 2  (these are vertical lines)

   y = b  --->  examples:  y = 5  or  y = 0  or  y = -2.5 (these are horizontal lines)

   y = mx + b  --->  examples:  y = 2x - 7  or  y = -5x + 9  or  y = -x + ½  (these are diagonal lines)