c) x^2 -x +1/ x = x^3 +1/ x(x+1) .
c) .
c) Ta có (x2 – x + 1) . x(x + 1) = x(x + 1)(x2 – x + 1) = x(x3 + 1);
Vì (x2 – x + 1) . x(x + 1) = x(x3 + 1) nên .