A= 1-2+3-4+...+59-60
=(1-2)+(3-4)+...+(59-60)
=-1+(-1)+...+(-1)
=(-1)*30
= -30
Đáp án : -30
( 1- 2 ) + ( 3 - 4 ) + ....+( 59 - 60 )
= ( -1 ) + ( -1 ) + .....+ ( -1 )
= Từ 1 đến 60 có 60 số. Vậy có 30 tổng ( số hạng ).
=> Nên tổng trên có kết quả là : ( -1 ) * 30
= -30
Vậy đáp án là -30.
A=1-2+3-4+....+59-60
B=\(\frac{-3}{20}\)- \(\frac{3}{200}\)- \(\frac{3}{2000}\)- \(\frac{3}{20000}\)
a) 57+58+59+60+61-17-18-19-20-21
b) 9-10+11-12+13-14+15-16
c) -1-2-3-4-5-.....-1999-2000-2001-2002
mọi người ơi pls help me
1) -10/11 . 8/9 + 7/18 . 10/11 2) 12/25 . 23/7 - 12/7 . 13/25 3) 3/7 . 16/15 - 2/15 . -3/7 4) -4/13 . 5/17 + -12/13 . 4/17
Bài 1: Tính
a) -7/9 . 2/3/4 (2/3/4 là hỗn số : 2 là số nguyên, 3/4 là phân số)
b) 2/3 + 1/3 . (-2/5)
c) 3/4 . 15/1/3 - 3/4 . 43/1/3
d) (-49,1) . 13/27 - 58,9 . 13/27
e) 0,375 : (-4,5)
f) 3/1/7 : (-1/3/7)
g) 9/1/3 : 4/2/3 - 2
h) (7/3/4 : 0,3125 + 4,5 . 2/2/45) : (-8,5)
Bài 2: Tính giá trị biểu thức
A = (-6/11) . 7/10 . (11/-6).(-20)
B = (-1/9) . (-17/29) . 58/51
C = (-3/7) . 5/11 + (-5/14) . 5/11
D = (1/1/27 . 12/23 . 9/14) : (-3/23)
Bài 3: Tìm x
a) 3/7 . x - 2/5 . x = -17/35
b) (3/4 . x -9/16) . [1/3 + (-3/5) : x] = 0
c) (x + 3/5) . (x + 1) = 0
Tính:
a) -5/7(14/5 - 7/10) : |-2/3| - 3/4(8/9 + 16/3) + 10/3(1/3 + 1/5)
b) 17/-26(1/6 - 5/3) : 17/13 - 20/3(2/5 - 1/4) + 2/3(6/5 - 9/2)
c) -8/9(9/8 - 3/2) + 5/4 : (5/2 - 15/4) - 3/4(10/9 - 8/3) : (-1/3)
d) 21/10 : (12/5 - 9/10) . (-4/7) - 3/2(1/6 - 7/12) + 1/5(3/2 - 1/4)
Tính giá trị biểu thức
\(1.A=\frac{1}{5}+\frac{3}{17}-\frac{4}{3}+\left(\frac{4}{5}-\frac{3}{17}+\frac{1}{3}\right)-\frac{1}{7}+\left[\frac{-14}{30}\right]\)
\(2.B=\left(\frac{5}{8}-\frac{4}{12}+\frac{3}{2}\right)-\left(\frac{5}{8}+\frac{9}{13}\right)-\left[\frac{-3}{2}\right]+\frac{7}{-15}\)
\(3.C=\frac{5}{18}+\frac{8}{19}-\frac{7}{21}+\left(\frac{-10}{36}+\frac{11}{19}+\frac{1}{3}\right)-\frac{5}{8}\)
\(4.D=\frac{1}{9}-\left[\frac{-5}{23}\right]-\left(\frac{-5}{23}+\frac{1}{9}+\frac{25}{7}\right)+\frac{50}{14}-\frac{7}{30}\)
\(5.E=\frac{1}{13}+\left(\frac{-5}{18}-\frac{1}{13}+\frac{12}{17}\right)+\left(\frac{12}{17}+\frac{5}{18}+\frac{7}{5}\right)\)
\(6.F=\frac{15}{14}-\left(\frac{17}{23}-\frac{80}{87}+\frac{5}{4}\right)+\left(\frac{12}{17}-\frac{15}{14}+\frac{1}{4}\right)\)
\(7.G=\frac{1}{25}-\frac{4}{27}+\left(\frac{-23}{27}+\frac{-1}{25}-\frac{5}{43}\right)+\frac{5}{43}-\frac{4}{7}\)
\(8.H=\frac{4}{15}-\frac{23}{28}-\left(\frac{-23}{28}+\frac{-11}{15}-\frac{29}{27}\right)-\frac{2}{27}\)
\(9.K=\frac{1}{16}-\frac{5}{21}+\left(\frac{-1}{16}+\frac{-3}{5}-\frac{-5}{21}\right)+\frac{-2}{5}+\frac{3}{4}\)
\(10.L=\frac{7}{12}+\frac{15}{14}-\left(\frac{14}{22}+\frac{-1}{14}+\frac{5}{21}\right)-\frac{-5}{21}+\frac{3}{5}\)
1.Tìm x :
a)1 - 7x = 3x - 4
2.Tính
a)-2013 . 2028 + 4028 . 26
b)\(\left(\frac{1515}{1616}+\frac{10}{170}\right)-\left(\frac{150}{160}-\frac{16}{17}\right)\)
c)\(\frac{1}{3^1}+\frac{1}{3^2}+\frac{1}{3^3}+...\frac{1}{3^{99}}\)
d)\(\frac{5}{17}+\frac{-4}{7}-\frac{20}{31}+\frac{12}{17}-\frac{11}{31}\)
e)\(\frac{155-\frac{10}{7}-\frac{5}{11}+\frac{5}{23}}{403-\frac{20}{7}-\frac{13}{13}_{ }+\frac{13}{23}}\)
-3/20-3/200-3/2000-3/20000
1.Thực hiện phép tính:
a)24^3:3^4-32^12:16^12
b) (2^31+2^27):(2^14x2^13)
c)(2^43+2^4):(2^39+1)
d)(2^23+2^24+2^25):(2^18+2^19+2^20)
e)(3^6x5^7x7^11):(3^4x5^7x7^10)
f)(2^7x3^4+2^9x3^5):(2^6x3^3x13)
g)(3^12+3^13):3^10
h)(4^17+4^3):(4^16+4^2)
