Question

A quadratic equation is written in four equivalent forms below. I. y = (x - 1)2 - 49 II. y = x2 - 2x - 48 III. y = (x + 6)(x - 8) IV. y = x(x - 2) - 48 Which of the forms shown above would be the most useful if attempting to find the x-intercepts of the quadratic equation?

Answer 1

The x-intercept also known as the root of a quadratic can be found by solving the equation with respect to x.

III is the most useful for finding the roots
you would simply equate each term to 

So y= x + 6                               AND                    y= x - 8        
     0= x + 6                                                           0= x - 8
      x= -6                                                                x= 8
 
: . x-intercepts are x= -6 & x= 8