Abstract. Let f P C r pr´1, 1sq, r ≥ 0 and let L˚be a linear right fractional differential operator such that L˚pf q ≥ 0 throughout r´1, 0s. We can find a sequence of polynomials Qn of degree ≤ n such that L˚pQnq ≥ 0 over r´1, 0s, furthermore f is approximated right fractionally and simultaneously by Qn on r´1, 1s. The degree of these restricted approximations is given via inequalities using a higher order modulus of smoothness for f prq .