Question

Calculati folosind factorul comun:72×27+27×28+(39×93-39×66); 1897×109-1897×100-1897×7-1897; 1977×315+1977×475+1977×1210; 1462×17-1462×16-1462; 1300×29-29×1299-29; 238×432+238×68-238×400.

Answer 1

1)
72x27+27x28+(39x93-39x66)=
27(72+28)+39(93-66)=
27x100+39x27=
27(100+39)=3753
2)
1897x109-1897x100-1897x7-1897=
1897(109-100-7)-1897=
1897x2-1897=
3794-1897=1897
3)
1977x315+1977x475+1977x1210=
1977(315+475+1210)=
1977x2000=3954000
4)
1462x17-1462x16-1462=
1462(17-16)-1462=
1462x1-1462=0
5)
1300x29-29x1299-29=
29(1300-1299)-29=
29x1-29=0
6)
238x432+238x68-238x400=
238(432+68-400)=
238x100=23800