Quadratic Functions

Question

Consider the Quadratic function .I

its vertex is ( ,  ).

its largest -intercept is   .



its -intercept is  

Answer 1

y=x^2 -3x -18

complete the square to get

y= x^2 -3x + 9/4 - 18 - 9/4

y=(x-3/2)^2 - 81/4

vertex is (3/2, -81/4)

x-intercept is the value of x when y=0

(x-3/2)^2 -81/4 =0

x-3/2 = + or - sqr(81/4) = + or - 9/2

x = 3/2 + or - 9/2 = -3 or 6

x= 6 is the largest x-intercept