Cac tong sau co la so chinh phuong khong ?
a) 11 * 13 * 15 * 17 * 19 + 2
b) 4 * 5 * 6 * 7 * 8 * 9
c) 152018 + 3
d) 20162019 - 3
e) 112019 + 52019 + 162019
Nho cac ban giai gium
Tính
A = 1 - 2 + 3 - 4 + 5 - 6 + 7 - 8 + 9 - ........... + 2019
B = 1 + 2 - 3 + 4 - 5 + 6 - 7 + .............. + 2017 + 2018 - 2019 + 2020
Tính S = 1 - 2 - 3 + 4 + 5 - 6 - 7 + 8 +...+ 2016 + 2017 - 2018 - 2019 + 2020
2+3-4+5+6-7+8+9-10+...+2015+2016-2017+2018+2019-2020+2021+2022
Chứng minh A=2019+2019^2+2019^3+2019^4+2019^5+2019^6 chia hết cho 2.
tính hợp lí
1-2-3-4+5-6-7-8+.........-2016+2017-2018-2019-2020
mấy bn giúp mk vs
1351+1452
14100-13100+20193
20174-20143
20192017-20182015
201915+202016+202317
201513+201614+201715
22019+32025
203150+203251
27+284+295
134+143+176
GIÚP MÌNH NHANH NHA MÌNH CẦN GẤP
bài 1: A=1-2+3-4+5-6+...+2017-2018+2019 ; B= (-1)+2-3+4-5+6-...-2017+2018-2019
bài 2: (-1)+3+(-5)+7+...+x=600
giúp mik với mai mik đi học rùi
1. 2019/2020-(2019/2020-2020/2021)
2.2/9+7/9 :(42/5-7/5
3.a)3/4+x/4=5/8
4./3x+1/-1/4=-1/4