Find four solutions of tan(2x^2 + x − 1) = 5

I work this out to:

2x^2 + x -2.373 = 0

Use the quadratic formula to get x= .8676, -1.3676

I don't know how to find two other answers since I don't the period.

If it didn't have x^2 I could put it in the form: A tan((2pi/B)(x-C)+D where B is the period.

How does one find the other solutions?