( n√a) m can be written as am/n .....so.....
5(√a5 ) = a5/5 = (a1/5)5 = a ⇒ Answer C
Second one
3√ [216a3b9 ] = 3√216 * 3√a3 * 3√b9 = (63)1/3 * (a3)1/3 * (b9)1/3 =
6ab3 ⇒ Answer C
Last one....look at answer B
√[98 j9c8] = √{49*2] * √ [j9 ] * √[c8 ] =
√49 * √2 * √ [j8] * √j * √[c8 ] =
7 * √2 * (j8)1/2 * √j * (c8)1/2 =
7j4c4√[ 2j ]