f(x)=(x+1-5)(x+1)^(2/3)f(x)=(x+1)^(5/3) - 5(x+1)^(2/3)f'(x)=5/3 (x+1)^(2/3) - 10/3 (x+1)^(-1/3)=0(x+1)^(2/3)-2(x+1)^(-1/3)=0(x+1)^(2/3)/(x+1)^(-1/3)=2(x+1)^(2/3+1/3)=2x+1=2x=1
