how do you find the zero of an equation with a constant in front of the squared variable? (y=2x^2+5-3)

I'm assuming that the problem is:  y  = 2x² + 5x - 3

This problem can be factored:                (2x - 1)(x + 3)  =  0

                  --->                                       2x - 1  =  0          or          x + 3  =  0

                  --->                                              x  =  1/2       or                 x  =  -3

This problem can also be solved by using the quadratic formula or by completing the square.

By the manner that you asked the question, are you supposed to complete the square?