# Thread: finding x intercept and completing the square

1. ## finding x intercept and completing the square

find x-intercepts

y=(x-1)squared + 2

y= (x+1)squared -1

completing the square

2xsquare -4x +1 =0
3xsquare - 5x -2=0

thank you

2. Put y=0 and obtian the values of x
2) 2x^2-4x+1=0
divd both sides by 2
x^2-2x+1/2=0
x^2-2x+1/2+1=1
(x-1)^2+1/2=1
(x-1)^2=1/2
do other similarly

3. Originally Posted by white
find x-intercepts

y=(x-1)squared + 2

y= (x+1)squared -1

completing the square

2xsquare -4x +1 =0
3xsquare - 5x -2=0

thank you
$y=(x-1)^2 + 2$
$y=x^2 -2x +3$
$b^2 - 4ac = (-2)^2 - 4(1)(3) = 4-12 = -8 < 0$
The discriminant is less than 0 which means that it does not cross the x-axis hence you won't have x-intercepts.
Try the other equation yourself by checking the discriminant for the nature of the curve. If it's greater than or equal to zero then it will have x-intercepts. To find it, make y equal to 0 and solve for x.

$2x^2 - 4x+1=0$
For quadratic equations in the form:
$ax^2+bx+c$
The general rule to completing the square is:
$a\left(x + \frac{b}{2a}\right)^2 - \frac{b^2}{4a} + c$
Use this rule to complete the square for your equations.