Quadratic functions

Question

By graphing the quadratic function f(x)=-3-2x+x2, find the x and y intercepts 

Answer 1

To find the x intercepts you would factor the equation to (x-3)(x+1)=0 and then since if either value in the parenthesis equals zero the result equals zero (0 times any number equals 0) you would set each equal to 0.  x-3=0 and x+1=0 will yield the results of x=3 and x=-1 respectively.  These are the x-intercepts because the y value equals zero at both these points. 

 

x-intercepts are:  (3,0) and (-1,0)

 

Since the y-intercepts are on the y-axis and the x values on any point on the y axis are 0 if you plug in a zero for x into the original equation you will get the y-intercept(s).  In this case you would get y=-3. 

 

y-intercept is: (0,-3)