Question

I. Tính hợp lí
1. -25x72+25x21-49x25

2, 8154-(674+8154)+(-98+674)

3, -25x21+25x72+49x25

4, (-1911)-(1234-1911)

5, (-1945)-(567-1945)

6, 44x(-36)+22x(-28)

Answer 1

1,-25x72+25x21-49x25

=25x(-72)+25x21-49x25

=25x(-72+21-49)

=25x(-100)=-2500

2,8154-(674+8154)+(-98+674)

=8154-674-8154-98+674

=(8154-8154)+(-674+674)-98

=0+0-98

=-98

3,-25x21+25x72+49x25

=25x(-21)+25x72+49x25

=25x(-21+72+49)

=25x100=2500

4,(-1911)-(1234-1911)

=(-1911)-1234+1911

=(-1911+1911)-1234

=0-1234=-1234

5,(-1945)-(567-1945)

=(-1945)-567+1945

=(-1945+1945)-567

=0-567=-567

6,44x(-36)+22x(-28)

=22x2(-36)+22x(-28)

=22x(-72)+22x(-28)

=22x(-72-28)=22x(-100)=-2200