Nguyễn Thị Hương giang
Giới thiệu về bản thân
4.103 + 5.102 + 7.10
= 4.10.102 + 5.102 + 70
= 40.102 + 5.102 + 70
= 102.(40 + 5) +70
= 100.45 + 70
= 4500 + 70
= 4570
a) 4/3; 18/19; 17/20; 0; -14/37; -14/33.
b) -2/3; -3/4; -7/8; -18/19; -27/28.
A) (-5/6) -(-1,8) + (-1/-6) - 0,8
= (-5/6) + (1,8) + 1/6 - 0,8
= (-5/6 + 1/6) + (1,8 - 0,8)
= 2/3 + 1
= 5/3.
B) (-9/-7) + (-1,23) - (-2/-7) - 0,77
= 9/7 + (-1,23) - 2/7 - 0,77
= (9/7 - 2/7) + (-1,23) - 0,77
= 1 + (-2)
= (-1).
a) 3/8. 11 + 3/11. 14 + ..... + 3/92. 95
= 1/8. 11 + 1/11. 14 + ..... + 1/92. 95
= 1/8 - 1/11 + 1/11 - 1/14 + ..... + 1/92 - 1/95
= 1/8 - 1/95
= 87/760.
b) 5/7. 12 + 5/12. 17 + ...... + 5/92. 97
= 1/7. 12 + 1/12. 17 + ...... + 1/92. 97
=1/7 - 1/12 + 1/12 - 1/17 + ...... + 1/92 - 1/97
= 1/7 - 1/97
= 90/679.
c) 3/1.2 + 3/ 2.3 + 3/ 3.4 + ......+ 3/99.100
= (1/1.2 + 1/2.3 + 1/3.4 + ......+ 1/99.100). 3
= (1 - 1/2 + 1/2 - 1/3 + 1/3 - 1/4 + ...... + 1/99 - 1/100). 3
= (1 - 1/100). 3
= 99/100 . 3
= 297/100.