Question

Вычеслите рациональным способом

Answer 1

2,8-3,1-4,9+4,2= 2,8+4,2-3,1-4,9= 7-8= - 1
$\frac{2}{7} \times 0.3 + 0.3 \times \frac{5}{7} = 0.3( \frac{2}{7} + \frac{5}{7}) = 0.3 \times 1 = 0.3$

Answer 2

а)2,8-3,1-4,9+4,2=(2,8+4,2)-(3,1+4,9)=7-8=-1

б)2/7×0,3+0,3×5/7=0,3(2/7+5/7)=0,3×7/7=0,3×1=0,3