Question 749990
b cube root 24a^5b + 3a cube root 81a^2b^4

24 = 8 *3
8 = 2^3

a^5 = a^3 *a^2

81 = 27*3
27 = 3^3

b^4 = b^3 * b

using that info rewrite the expression

b cube root (2^3 *3 *a^3 * a^2 *b) + 3 cube root (3^3 *3 *a^2 * b^3 *b)
 

b * 2 *a  cube root (3ba^2) + 3 * 3 *b cube root (3ba^2)

the expression now becomes
2ba cube root (3ba^2) + 9b cube root (3ba^2)
which can be simplified into

(2ba + 9b)cube root (3ba^2)