Question

find the x intercept of the parabola with vertex (-1,-16) and y intercept (0,-15) write your answer in this form (x1,y1), (x2,y2) Please help!!!!

Answer 1

Start by drawing a sketch to represent the parabola.
Since the y-intercept is higher than the vertex, the parabola is concave up.

The vertex (xv, yv) is a convenient way to write the equation of the parabola:
Equation for a parabola that is concave up or down (instead of left/right).
y-yv = a(x-xv)^2
given (xv,yv)=(-1,-16), we have the equation:
y-(-16) = a(x-(-1))^2
y=a(x+1)^2-16
To find the numerical value of a, we substitute the other known point (0,-15) into the equation and solve for a:
-15=a(0+1)^2-16
Solve for a= 1, so the equation of the parabola is:
y=(x+1)^2-16
To find the x-intercepts, solve for x in
y=(x+1)^2-16=0