Question

помогите пожалуста
71³+49³
----------. +. 71•49
120​

Answer 1

$\displaystyle\frac{71^{3} +49^{3} }{120} +71*49=\frac{(71+49)(71^{2} -71*49+49^{2}) }{120} +71*49=\\ \\ \frac{120(71^{2} -71*49+49^{2})}{120} +71*49=71^{2} -71*49+49^{2}+71*49=\\ \\ 71^{2}+49^{2} =(70+1)(70+1)+(50-1)(50-1)=\\ \\ 4900+2*70*1+1+2500-2*50*1+1=7442$