why do even degrees never cross the x-axis

Even degree polynomials can cross the x axis 

See the following :  https://www.desmos.com/calculator/fkd1kpcoui

The function that you have   ( x^2 + 3 - 1  =  x^2 + 2)   won't cross the x axis because it is the basic graph of y = x^2  shifted up 2 units.....so.....this will never cross the  x axis

ohhh thank you !