Question

вычислите наиболее рациональным способом. помогитеее

Answer 1

$\frac{ {71}^{3} + {49}^{3} }{120} - 71 \times 49 = \frac{(71 + 49)( {71}^{2} - 71 \times 49 + 49^{2} )}{120} - 71 \times 49 = {71}^{2} - 71 \times 49 + {49}^{2} - 71 \times 49 = {71}^{2} - 2 \times 71 \times 49 + 49^{2} = {(71 - 49)}^{2} = {22}^{2} = 484$