Question

Вычислите рациональным способом: 4*39-39*3.8+3.8*37-37*3.6+3.6*35-35*3.4+3.4*33-33*32

Answer 1

4*39-39*3.8+3.8*37-37*3.6+3.6*35-35*3.4+
+3.4*33-33*3,2=39(4-3,8)+37(3,8-3,6)+
+35(3,6-3,4)+33(3,4-3,2)=39×0,2+37×0,2+
+35×0,2+33×0,2=0,2(39+37+35+33)=
=0,2×144=28,8