Tính hợp lí 1/ (- 37) + 14 + 26 + 37; 2/ (- 24) + 6 + 10 + 24; 3/ 15 + 23 + (- 25) + ( - 23);
18
09/06/2024
Tính hợp lí
1/ (– 37) + 14 + 26 + 37;
2/ (– 24) + 6 + 10 + 24;
3/ 15 + 23 + (– 25) + ( – 23);
4/ 60 + 33 + (– 50) + (– 33);
5/ (– 16) + ( – 209) + ( – 14) + 209;
6/ (– 12) + ( – 13) + 36 + (– 11);
7/ 300 – (– 200) – (– 120) + 18;
8/ – (– 299) + (– 219) – 401 + 12;
9/ 555 – (– 333) – 100 – 80;
10/ 34 + 35 + 36 + 37 – 14 – 15 – 16 – 17;
11/ 1+ (– 2) + 3 + (– 4) + ..... + 19 + (– 20);
12/ 1 – 2 + 3 – 4 + ... + 99 – 100.
Trả lời
1/ (– 37) + 14 + 26 + 37
= [(– 37) + 37] + (14 + 26)
= 0 + 40 = 40
2/ (– 24) + 6 + 10 + 24
= (– 24 + 24) + (6 + 10)
= 0 + 16 = 16
3/ 15 + 23 + (– 25) + ( – 23)
= [15 + (– 25) + [23 + (– 23)]
= – 10 + 0 = – 10
4/ 60 + 33 + (– 50) + (– 33)
= [60 + (– 50)] + [33 + (– 33)]
= 10 + 0 = 10
5/ (– 16) + ( – 209) + ( – 14) + 209
= [(– 16) + (– 14)] + [(– 209) + 209]
= – 20 + 0 = – 20
6/ (– 12) + ( – 13) + 36 + (– 11)
= (– 25) + (– 11) + 36
= – 36 + 36 = 0
7/ 300 – (– 200) – (– 120) + 18
= 300 + 200 + 120 + 18
= 500 + 120 + 18
= 620 + 18
= 638
8/ – (– 299) + (– 219) – 401 + 12
= 299 – 219 – 401 + 12
= 80 – 401 + 12
= – 321 + 12 = – 309
9/ 555 – (– 333) – 100 – 80
= 555 + 333 – 180
= 888 – 180
= 708
10/ 34 + 35 + 36 + 37 – 14 – 15 – 16 – 17
= (34 – 14) + (35 – 15) + (36 – 16) + (37 – 17)
= 20 + 20 + 20 + 20
= 80
11/ 1+ (– 2) + 3 + (– 4) + ..... + 19 + (– 20)
=[1 + (– 2)] . [(20 – 1) : 1 + 1] : 2 = – 1 . 10 = – 10
12/ 1 – 2 + 3 – 4 + ... + 99 – 100
= (1 – 2) . [(100 – 1) : 1 + 1] : 2 = –1 . 50 = – 50
