Expand the left side first:
x^2+x-20=14
Subtract 14 from both sides:
x^2+x-34=0
Use the quadratic equation:
1) x= (-1 + sqrt(1-4(1)(-34)))/(2(1))
x = (-1 + sqrt(137))/2
2) x= (-1 - sqrt(1-4(1)(-34)))/(2(1))
x = (-1- sqrt(137))/2
For the general quadratic equation, for other similar problems, reference:
http://en.wikipedia.org/wiki/Quadratic_equation