Cho biết: \(1^3+2^3+3^3+....+10^3=1025\) Tính:
a) A = \(2^3+4^3+5^3+...+20^3\)
b) B = \(0,5^3+1^3+1,5^3+....+5^3\)
tính:A)2/3+20%.10/7
B) (2-1/2).(-3/4+1/2)
c)3/4 +1 và 4/5:3/2-1
d)1,5.(7/3 -5/3.4)
các bạn giải giúp mik nhá!mik đang cần gấp
a: =2/3+1/5*10/7
=2/3+2/7
=14/21+6/21=20/21
b: \(=\dfrac{1}{2}\cdot\dfrac{-3+2}{4}=\dfrac{1}{2}\cdot\dfrac{-1}{4}=\dfrac{-1}{8}\)
c: \(=\dfrac{3}{4}+\dfrac{9}{5}:\dfrac{3}{2}-1\)
=-1/4+9/5*2/3
=-1/4+18/15
=-1/4+6/5
=-5/20+24/20=19/20
d: \(=\dfrac{3}{2}\cdot\left(\dfrac{7}{3}-\dfrac{5}{3}\cdot4\right)\)
\(=\dfrac{7}{2}-\dfrac{5}{2}\cdot4=\dfrac{7}{2}-\dfrac{20}{2}=\dfrac{-13}{2}\)
Cho \(1^3+2^3+3^3+...+10^3=3025\)
Tính a) \(2^3+4^3+6^3+...+20^3\)
b)\(0,5^3+1^3+1,5^3+...+5^3\)
23 = (2.1)3 = 23. 13
43 = (2.2)3 = 23.23
63 = (2.3)3 = 23. 33
. . .
203 = (2.10) 3 = 23. 103
=> 23 + 43 + 63 +...+ 203
= 23. 13 + 23. 23 + 23. 33 + ... + 23 . 103
= 23. ( 13 + 23 + 33+ ... + 103)
= 23 . 3025
= 8. 3025
= 24200
So easyyyyyyyyyyyyyyyy
Cho biết:
13+23+33+...+103=3025
Tính: a)A=23+43+63+...+203
b) B= 0,53+13+1,53+...+53
a) \(2^3+4^3+6^3+...+20^3\)
\(=2^3\left(1+2^3+...+10^3\right)\)
\(=8\cdot3025\)
\(=24200\)
b) \(0,5^3+1^3+1,5^3+...+5^3\)
\(=0,5^3\left(1+2^3+...+10^3\right)\)
\(=0,125\cdot3025\)
\(=378,125\)
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)
a) Ta có: \(\dfrac{-5}{7}\left(\dfrac{14}{5}-\dfrac{7}{10}\right):\left|-\dfrac{2}{3}\right|-\dfrac{3}{4}\left(\dfrac{8}{9}+\dfrac{16}{3}\right)+\dfrac{10}{3}\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\)
\(=\dfrac{-5}{7}\cdot\dfrac{3}{2}\cdot\dfrac{21}{10}-\dfrac{3}{4}\cdot\dfrac{56}{3}+\dfrac{10}{3}\cdot\dfrac{8}{15}\)
\(=\dfrac{-9}{4}-14+\dfrac{16}{9}\)
\(=\dfrac{-1621}{126}\)
b) Ta có: \(\dfrac{17}{-26}\cdot\left(\dfrac{1}{6}-\dfrac{5}{3}\right):\dfrac{17}{13}-\dfrac{20}{3}\left(\dfrac{2}{5}-\dfrac{1}{4}\right)+\dfrac{2}{3}\left(\dfrac{6}{5}-\dfrac{9}{2}\right)\)
\(=\dfrac{-17}{26}\cdot\dfrac{13}{17}\cdot\dfrac{-3}{2}-\dfrac{20}{3}\cdot\dfrac{3}{20}+\dfrac{2}{3}\cdot\dfrac{-33}{10}\)
\(=\dfrac{3}{4}-1-\dfrac{11}{5}\)
\(=-\dfrac{49}{20}\)
Bài 1: Tìm x :A) 3/4.(x-2) - 1/2.(6-2.x)= 1/6.x + 5
B) -1/2.(3.x + 5) - 2/3.(9-6.x) = 3/5.(x-10) - 3
C) (1/4.x - 1,5) + (5/6.x - 3) - (5/8.x -0,5) = -4,5
Cho biết: 1\(^3\)+2\(^3\)+3\(^3\)+....+10\(^3\)=3025
a/ 2\(^3\)+4\(^3\)+6\(^3\)+....+20\(^3\)
b/0,5+1\(^3\)+1,5\(^3\)+...+5\(^3\)
a) Nhân 2 vế của đẳng thức đầu cho 23---> \(1^3.2^3+2^3.2^3+...+10^3.2^3=3025.2^3\)
\(\Rightarrow2^3+4^3+...+20^3=3025.8=24200\)
b Chia 2 vế của đẳng thức đầu cho 23---> \(\frac{1^3}{2^3}+\frac{2^3}{2^3}+...+\frac{10^3}{2^3}=\frac{3025}{2^3}\)
\(\Rightarrow0,5^3+1^3+2^3+...+5^3=\frac{3025}{8}=378,125\)
Bài 1: Tìm x : A) 25%x+4x=35-0,75x
B) 3/4.(x-2) - 1/2.(6-2x)=1/6x + 5
C) -1/2.(3x+5) - 2/3.(9-6x)= 3/5.(x-10) - 3
D) (1/4x - 1,5) + (5/6x-3) - (5/8x-0,5)= -4,5
Biết 13+23+33+...+103= 3025
Tính A= (0,5)3+13+(1,5)3+...+53
B= (0,25)3+(0,5)3+(0,75)3+...+(2,5)3
Thực hiện phép tính : a) (9 và 4/9+5 và 2/3)-5 và 1/2 b) 13/9.15/4-13/9.7/4-13/9.5/4 c) 2/3+5/8-(-1)/3+0,375 d) 75%-3 và 1/2+1,5:10/7 e) 1 và 13/15.(0,5)^2.3+(8/15-1 và 19/60):1 và 23/24
Giải:
a) \(\left(9\dfrac{4}{9}+5\dfrac{2}{3}\right)-5\dfrac{1}{2}\)
\(=\left(\dfrac{85}{9}+\dfrac{17}{3}\right)-\dfrac{11}{2}\)
\(=\dfrac{136}{9}-\dfrac{11}{2}\)
\(=\dfrac{173}{18}\)
b) \(\dfrac{13}{9}.\dfrac{15}{4}-\dfrac{13}{9}.\dfrac{7}{4}-\dfrac{13}{9}.\dfrac{5}{4}\)
\(=\dfrac{13}{9}.\left(\dfrac{15}{4}-\dfrac{7}{4}-\dfrac{5}{4}\right)\)
\(=\dfrac{13}{9}.\dfrac{3}{4}\)
\(=\dfrac{13}{12}\)
c) \(\dfrac{2}{3}+\dfrac{5}{8}-\dfrac{-1}{3}+0,375\)
\(=\left(\dfrac{2}{3}-\dfrac{-1}{3}\right)+\left(\dfrac{5}{8}+\dfrac{3}{8}\right)\)
\(=1+1\)
\(=2\)
d) \(75\%-3\dfrac{1}{2}+1,5:\dfrac{10}{7}\)
\(=\dfrac{3}{4}+\dfrac{7}{2}+\dfrac{3}{2}:\dfrac{10}{7}\)
\(=\dfrac{3}{4}+\dfrac{7}{2}+\dfrac{21}{20}\)
\(=\dfrac{53}{10}\)
e) \(1\dfrac{13}{15}.\left(0,5\right)^2.3+\left(\dfrac{8}{15}-1\dfrac{19}{60}\right):1\dfrac{23}{24}\)
\(=\dfrac{28}{15}.\dfrac{1}{4}.3+\left(\dfrac{8}{15}-\dfrac{79}{60}\right):\dfrac{47}{24}\)
\(=\dfrac{7}{5}+\dfrac{-47}{60}:\dfrac{47}{24}\)
\(=\dfrac{7}{5}+\dfrac{-2}{5}\)
\(=1\)