What is integral value?What is integral formula?Is there an integral formula?Can an integral equal 0

Evaluate ∫(z^2-z+1)/(z-1) where C is circle |z|=1/2 is ? where c is |z|=1.,where c is |z|=3,evaluate ∫(z-3) /(z^2+2z+5) dz,integral (e^piz/(2z-i)^3)dz c circle |z|=1 cauchy riemann,evaluate integral (e^3z/z^2)dz over |z|=1 cauchy riemann,evaluate integral ((z^2+z+1)/(z-2)^3)dz cauchy,z/(z^2-4) |z|=1 |z|=3,evaluate integral (e^2z/((z+1)^2(z-2)))dz cauchy,integral dz/(z^2-4) |z|=1 |z|=3 cauchy,cauchy riemann evaluate integral ((z^2+z+1)/(z-2)^3)dz,evaluate closed line integration 1/z-2w.r t. z along the circle |z-2|=4.