Hi,  

the vertex form of a parabola,  where(h,k) is the vertex

vertex (4,-1)

y =a(x-4)^2 -1

using y-intercept pt(0,15) to find a

15 = a(-4)^2 - 1

16 = a*16

 1 = a

y = (x-4)^2 - 1  OR y = x^2 - 8x + 15

x^2 - 8x + 15 = 0

factoring

(x-3)(x-5) = 0

(x-3) = 0   x = 3

(x-5) = 0   x = 5

x-intercepts are Pt(3,0) and pt(5,0)



 

RELATED QUESTIONS

Find the x intercepts of the parabola with vertex (1,-13) and y intercept... (answered by lwsshak3)

Find the x-intercepts of the parabola with vertex (4,-1) and y-intercept... (answered by Fombitz)

find the x intercepts of the parabola with vertex (-1,-16) and y intercept (0,-15). use... (answered by Fombitz,Boreal)

Find the x-intercepts of the parabola with vertex of (-4,2) and y-intercept (0,-30).  (answered by josmiceli)

Find the x-intercepts of the parabola with vertex (-5,80) and y-intercept... (answered by ewatrrr)

find the x-intercepts of the parabola with vertex (1,1) and y-intercept(0,-3)
 (answered by lwsshak3)

find the x-intercepts of the parabola with vertex (-3,16) and y-intercept (0,-20).
 (answered by Fombitz)

Find the x-intercepts of the parabola with vertex (-1,-108)and y- intercepts (0,-105).   (answered by Fombitz)

find the x-intercepts of the parabola with the vertex (1,-13) and a y-intercept... (answered by solver91311)