If 7, J are two ideals of a commutative ring R. Define rad(1) = {a e R: 3n E N such that a" E I} Then prove that (a) rad(1) is an ideal of R containing I. (b) rad()+ rad(J) C radrad(I) + rad(J)] = rad(I + J). (c) if T" S J for sonme n E N, then rad(1) S rad(J)