Roots are numbers that make an expression equal to zero. If it's an
equation like y = mx + b or
y = ax2+bx+c or any other
equation involving x and y, the roots are those points where the graph
crosses the x-axis.
Example 1: y = 2x - 3. The root
of this equation is 1.5
y = 2x2 - x - 15. The roots
of this equation are -2.5 and 3.