Помогите пожалуйста! Маленькое задание во вложении

Если $a^ \frac{1}{3}-b^ \frac{1}{3} \neq 0$ ;
$a \neq b$ , то:

$\frac{a^ \frac{4}{3}b-ab^ \frac{4}{3}}{a^ \frac{1}{3}-b^ \frac{1}{3}} = \frac{a^ {1+\frac{1}{3}}*b-a*b^{1+ \frac{1}{3}}}{a^ \frac{1}{3}-b^ \frac{1}{3}} = \frac{a^1*a^ {\frac{1}{3}}*b-a*b^1*b^{\frac{1}{3}}}{a^ \frac{1}{3}-b^ \frac{1}{3}} =$
$= \frac{a*a^ {\frac{1}{3}}*b-a*b*b^{\frac{1}{3}}}{a^ \frac{1}{3}-b^ \frac{1}{3}} = \frac{a*b*a^ {\frac{1}{3}}-a*b*b^{\frac{1}{3}}}{a^ \frac{1}{3}-b^ \frac{1}{3}} = \frac{(a*b)*a^ {\frac{1}{3}}-(a*b)*b^{\frac{1}{3}}}{a^ \frac{1}{3}-b^ \frac{1}{3}} =$
$= \frac{(a*b)*(a^ {\frac{1}{3}}-b^{\frac{1}{3}})}{1*(a^ \frac{1}{3}-b^ \frac{1}{3})} = \frac{(a*b)}{1} =(a*b)=a*b=ab$