posted by Mary .
Explain how to use a graph to determine the number of solutions of a system?
Plot the graph of the function f(x), and find out where the graph intersects the x-axis, which means that f(x)=0, or a real solution exists. The corresponding value of x is a real root of the equation.
Note that complex roots, if any, are not shown on a graph. Also, multiple roots are not so obvious. The x-axis may appear as a tangent to the curve.