y=x(x+1)^(1/2)*(x+2)^(-2)
y'=(x+1)^(1/2)*(x+2)^(-2)+(1/2)x(x+1)^(-1/2)*(x+2)^(-2)-2x(x+1)^(1/2)*(x+2)^(-3)
=(2-x)(x+2)^(-3)+(1/2)x(x+1)^(-1/2)*(x+2)^(-2)