how do I solve gradient f(x,y) with range (-5>x,y>5)

f(x,y) = (7 / ((x-2)^2 + (y-2)^2+1)+ 6 / ((x-2)^2 + (y+2)^2+1)+ 5/((x+2)^2 + (y-2)^2+1)

please help me to learn