To solve this problem you must aply the proccedure shown below:
You have the following quadratic equation: a^2-a+11=0 and to solve it you must apply the quadratic formula x=-b√(b^2-4ac)/2a
a=1
b=-1
c=11
The result is
a1=(1-i√43)/2
a2=(1+i√43)/2
The answer is:a1=(1-i√43)/2 and a2=(1+i√43)/2