How to obtain root of this quadratic equation

I got this quadratic equation in a problem $T^2 - 2T - 40 = 0$, but i am unable to find the roots of this equation. Is any other concept hidden in this equation? Please help.

I am basically a Bipc [biology physics and chemistry] student of India and do not have a good mathematical base.

If you do not know the solution of quadratic equations and want to solve $$x^2-2x-40=0$$ start completing the square writing $$x^2-2x-40=x^2-2x+1-40-1=(x-1)^2-41=0$$ So, $$x-1=\pm\sqrt{41}$$ and so $$x=1\pm\sqrt{41}$$