a) A=100+98+96+...+2+-97+-95+...+-1
A=(2+-1)+(4+-3)+(6+-5)+...+(98+-97)+100
A=1+1+1+1+1+...+1 + 100 (49 chữ số 1)
A= 49 +100
A= 149
b)B=(27.45+27.55):(2+4+6+...+14+16+18)
B= 27.(45+55): (18+2).((18-2):2+1):2
B= 27.100 : 90
B= 2700 : 90
B= 30
Cố lên muôn năm
Tính hợp lí
a) (27.45+27.55):(2+4+6+...+14+16+18)
b) (27.700-24.45.20):(45-40+35-30+25-20+15-10+5)
B2: Tính tổng
A=24+25+26+...+122 C=100-99+98-97+96-95+...+2-1
B=12+15+18+21+...+1995 D=1+3+5+7+...+2021
giúp mình nha
tính hợp lí;
a)45.16-17:28+45.15
b)27.45+27.55:2+4+6+8+........+16+18
\(a.\frac{27.45+27.55}{2+4+6+...+14+16+18}\)
\(b.\frac{26.108-26.12}{32-28+24-20+16-12+8-4}\)
\(c.\frac{27.4500+135.550.2}{2+4+6+...+14+16+18}\)
\(d.\frac{48.700-24.45.20}{45-40+35-30+25-20+15-10+5}\)
Tính bằng cách thuận tiện nhất :
a, 1 - 2 + 3 - 4 + 5 - 6 + ... + 97 - 98 + 99 - 100 + 101
b, 10 - 12 + 14 - 16 + 18 - 20 + ... + 90 - 92 + 94 - 96 + 98
c, 1 - 4 + 7 - 10 + 13 - 16 + ... + 85 - 88 + 91 - 94 + 97
A.100-99+98+97+96+95+...+4-3+2-1
B.100-98+96-94+...+4-2
a) A=1-2+3-4+5-6+.........+99-100+101
b) B=1+4+5+9+14+......+60+97
c) C=100+98+96+....+2-97-95-.......-1
d) D=1+2-3-4+5+6-7-8+9+10-11-12+.......+299-300+301+302
1)Tính nhanh
a) (56.27+56.35):62
b)884.48-432:96/864.48.432
c)45.16-17/28+45.15
d)27.45+27.55/2+4+6+........+18
2) Tìm X thuộc N , biết:
a)[(6.X-39):3].28=5628
b)(16.15):2=(X+70).14-20
c)6060:50.X+20/X=101
\(A={27.45+27.55 /2+4+6+8+...+16+18}\)
B=135.1420+45.780.3/ 3+6+9+12+...+24+27
C=24347.78-26.4.3.6000/ 4+5+6+7+...+24+25+26
