Can anyone solve this quadratic equation

y = 2x² - 6

2. Can't really 'solve' this, but I think you meant

2x² - 6 = 0
2(x² - 3) = 0
x² = 3
x = $\pm \sqrt 3$

If you really wanted to solve y = 2x² - 6

2x² - (6+y) = 0
2x² = 6 + y
x² = 0.5 (6+ y)
x = $\pm \sqrt {\frac{1}{2} (6+y)}$