how can i get the x-intercepts using this formula y= 2(x-1)^2-18

Question

Find The co-ordinates of A and B of whic are x cordinates using the formula y=2(x-1)^2-18

Answer 1

When finding an x intercept, set y equal to 0

0=2(x-1)^2 - 18                

0= 2(x^2 - x-x +1) - 18    combine like terms and distribute

0= 2x^2 - 4x +2 - 18        combine like terms

0= 2x^2 - 4x -16              remove the common factor

0= 2(X^2 -2x - 8)             foil, common factors 8= 2 and 4 and 4= 4-2, 4 needs to be negative to get this -2

0=  2(x-4) (x+2)                solve for x

0 = x-4          add 4 on both sides x=4                0= x+2          sunbtract 2 on ach side x= -2

 

Or you could put it into a graphing calculator. Also use the quadratic formula if you cannot find the roots.