The x-intercept/s of the graphs are the value of x at which the y of the equation is equal to zero. Substituting zero to the y of the equation given above,
0 = x² + 3x - 28
We can determine the values of x from the equation by factoring. The factors of x² + 3x - 28 are,
(x + 7) and (x - 4)
Substituting these to the given,
(x + 7)(x - 4) = 0
Determining the values of x,
1st: x + 7= 0, x = -7
2nd: x - 4 = 0, x = +4
The values of the x-intercept therefore lies at (-7,0) and (4,0).
The answer to this item is letter D.
