## Fixed Point Iteration for f(x)=cos(x+(2)^(1/2))+x(x/2+(2)^(1/2))=0 on [-2,-1]?

I need a function g(x)=x such that the fixed point iteration converges to the root of the equation in the title (the root is -(2)^(1/2)). So |g'(x)|<1 on [-2,-1]. Thank you!