X2-2x-13=0 How Do U Solve This Please Im Lost?

I assume x2 is supposed to be x squared

x^2 -2x -13 = 0

x = -b +- sqrt(b^2-4ac) all over 2a
= 2 +- sqrt(4-4.-13) all over 2
= 2 +- sqrt(56) all over 2
= 2 +- 7.48 all over 2
= 1 +- 3.74
x = 4.74 or -2.74

I could be wrong tho - bit rusty at this stuff

anyone?