How do I solve these equations?

f1=(1+x^2)*(sqrt(x)+3)
f2=a+log(b+x^2)
f3=1/(sqrt(x^2+y^2)
f4=sin(a+x^2)+cos(b+y^2)
x=1/2
y=5
a=0.1
b=2

I want to define and solve these equations with these functions (inline , feval ,eval,fittype,@)