What are the roots of the equation 2x^2-1=0

2x² - 1 = 0
2x² = 1
x² = 1/2
x = ± √(1/2)
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The roots are where the y value is 0. There's no y in this question, so I'm assuming either you or the person who made the question has already done this:
2x^2-1=y and 0=y, so 2x^2-1=0.

You just need to solve for x here:
2x^2-1=0
2x^2=1
x^2=1/2
x= sqrt(1/2), or -sqrt(1/2)

2x^2 - 1 = 0
quadratic formula:
x = [+/- SQR(-4(2)(-1))]/2(1)
x = (+/- 2SQR(2))/2
x = +/- SQR(2)

- .--

2x^2-1=0
x^2-1/2=0
x^2=1/2
x=+sqrt(1/2),-sqrt(1/2)

2x^2=1
x=1/sqrt2
or
x=-1/sqrt2