Question #f78a9

1 Answer
Dec 26, 2014

When you have a quadratic function #y=ax^2+bx+c# to find the #x# intercepts you must set the value of #y# equal to zero (a point on the #x# axis, the intercept, must have coordinate #y# equal to zero otherwise it doesn't lie on the #x# axis).
But, when #y=0# in your function you are left with: #ax^2+bx+c=0# which is a quadratic equation.
If you solve this equation you'll find (possibly) two values of #x_1 and x_2#.
Your x-intercepts will then be the points of coordinates:
#(x_1,0)#
#(x_2,0)#

Consider the following example:
enter image source here

Important:
It is possible that your second degree equation might not have solutions or have one solution only, depending upon the value of #Delta=b^2-4ac# of your particular equation.