hello : the parabola's equation is : f(x) = a(x+1)²+16 the coefficient of the squared expression in the parabola's equation is : a but ; f(0) = 15 ... ( y-intercepts (0,15) )
15 = a(0+1)²+16 15 =a +16
a=-1 f(x) = -(x-1)²+16
the x-intercepts when : f(x) =0 -(x-1)²+16=0 (x-1)² =16=4² x-1 = 4 or x-1 = -4 x=5 or x=-3
are the x-intercepts two points : (5 , 0 ) ; (-3 ; 0)