tính:S=2-5+8-11+...-29+32
Tính:S=1+1/2+1/4+1/8+1/16+1/32+...
\(S=1+\frac{1}{2}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+....\)
\(S=1+\frac{1}{1.2}+\frac{1}{2.4}+\frac{1}{4.4}+\frac{1}{4.8}+...\)
\(S=1+1-\frac{1}{2}+\frac{1}{2}-\frac{1}{4}+\frac{1}{4}-\frac{1}{4}+\frac{1}{4}-\frac{1}{8}+....\)
( GẠCH BỎ CÁC PHÂN SỐ GIỐNG NHAU)
MK KO BIẾT!!!!!
S = 6 /2×5+6/5×8+6/8×11+...+6/29+32-1/n-1n+1=n×(n+1)
có sai đề bài ko vậy
Có ai giúp tớ không Tính nhanh 2+5+8+11+....+29+32
Kc:3
số số là:
(32-2):3+1=11(số)
Tổng là:
(32+2)x11:1=187
2 + 5 + 8 + 11 + ... + 29 + 32 .
Ta có :
2 + 5 + 8 + 11 + ... + 29 + 32 ( có 11 số hạng )
= (32 + 2) x 11 : 2 = 187
Bài 1:Tính
a,3/2+5/4+5/8
b,4/5-3/8+2/4
c,3+6/8-5/4
d,5/6-1/2+2
e,3/5+6/11+7/13+2/5+16/11+19/13
g,75/100+18/21+29/32+1/4+3/21+13/32
Giusp mình nhé
a.\(\dfrac{27}{8}\)
b.\(\dfrac{37}{40}\)
c.\(\dfrac{5}{2}\)
d.\(\dfrac{7}{3}\)
e.5
g.\(\dfrac{53}{16}\)
Bài 1 :
a) \(\dfrac{3}{2}+\dfrac{5}{4}+\dfrac{5}{8}=\dfrac{12}{8}+\dfrac{10}{8}+\dfrac{5}{8}=\dfrac{12+10+5}{8}=\dfrac{27}{8}\)
b) \(\dfrac{4}{5}-\dfrac{3}{8}+\dfrac{2}{4}=\dfrac{32}{40}-\dfrac{15}{40}+\dfrac{20}{40}=\dfrac{32-15+20}{40}=\dfrac{37}{40}\)
c) \(3+\dfrac{6}{8}-\dfrac{5}{4}=\dfrac{3}{1}+\dfrac{6}{8}-\dfrac{5}{4}=\dfrac{24}{8}+\dfrac{6}{8}-\dfrac{10}{8}=\dfrac{20}{8}=\dfrac{5}{2}\)
d) \(\dfrac{5}{6}-\dfrac{1}{2}+2=\dfrac{5}{6}-\dfrac{1}{2}+\dfrac{2}{1}=\dfrac{5}{6}-\dfrac{3}{6}+\dfrac{12}{6}=\dfrac{14}{6}=\dfrac{7}{3}\)
e) \(\dfrac{3}{5}+\dfrac{6}{11}+\dfrac{7}{13}+\dfrac{2}{5}+\dfrac{16}{11}+\dfrac{19}{13}=\left(\dfrac{3}{5}+\dfrac{2}{5}\right)+\left(\dfrac{6}{11}+\dfrac{16}{11}\right)+\left(\dfrac{7}{13}+\dfrac{19}{13}\right)=1+2+2=5\)
g) \(\dfrac{75}{100}+\dfrac{18}{21}+\dfrac{29}{32}+\dfrac{1}{4}+\dfrac{3}{21}+\dfrac{13}{32}=\dfrac{3}{4}+\dfrac{6}{7}+\dfrac{29}{32}+\dfrac{1}{4}+\dfrac{1}{7}+\dfrac{13}{32}=\left(\dfrac{3}{4}+\dfrac{1}{4}\right)+\left(\dfrac{6}{7}+\dfrac{1}{7}\right)+\left(\dfrac{29}{32}+\dfrac{13}{32}\right)=1+1+\dfrac{21}{16}=2+\dfrac{21}{16}=\dfrac{53}{16}\)
a,3/2+5/4+5/8 = 12/8 + 10/8 + 5/8 = 27/8
b,4/5-3/8+2/4 = 32/40 - 15/40 + 20/40 = 37/40
c,3+6/8-5/4= 24/8 + 6/8 - 10/8 = 20/8 = 5/2
d,5/6-1/2+2 = 5/6 - 3/6 + 12/6 = 14/6 = 7/3
e,3/5+6/11+7/13+2/5+16/11+19/13 = ( 3/5+ 2/5) + ( 6/11 + 16/11) + ( 7/13 + 19/13) = 1 + 2 + 2 = 5
g,75/100+18/21+29/32+1/4+3/21+13/32 = 3/4 + 6/7 + 29/32 + 1/4 + 1/7 + 13/32= ( 3/4 + 1/4) + ( 29/32 + 13/32) + ( 6/7 + 1/7)= 1 + 21/16 + 1 = 53/16
1. (-12)+(-15)+(-31) | 2. 25+37-59 | 3. (-12)+13-(-60)
4. 24:(-2)+(-5) | 5. 32.(-2)+64 | 6. 18.3+(-50):5
7. (-24)+37+163+(-176) | 8. 125+217+(-625)+529 | 9. 29+132+237+868+763
10. (-87)+126+187+74 | 11. 29.87+29.13 | 12. 123.(-29)-23.(-29)
13. 31.(-18)+31.(-81)-31 | 14.(-12).47+(-12).52+(-12) | 15. 24.(16-5)-16.(24-5)
16. 29.(29-3)-19.(29-13) | 17. -452-(-67+75-452) | 18. -(-171+89+223)-(71-111)+223
19. 21.83-3.7.(-17) | 20. 35-{12-[-14+(-2)]} | 21.5+10+15+20+....+1000
22. 3-6+9-12+....+195-198
\(\frac{9+\frac{9}{11}+\frac{18}{23}-\frac{27}{37}}{8+\frac{8}{11}+\frac{16}{23}-\frac{24}{37}}-\frac{2+\frac{16}{29}-\frac{24}{13}-\frac{32}{11}}{3+\frac{24}{29}-\frac{36}{13}-\frac{48}{11}}\)
Thuc hien phep tinh
Đặt \(A=\frac{9+\frac{9}{11}+\frac{18}{23}-\frac{27}{37}}{8+\frac{8}{11}+\frac{16}{23}-\frac{24}{37}}-\frac{2+\frac{16}{29}-\frac{24}{13}-\frac{32}{11}}{3+\frac{24}{29}-\frac{36}{13}-\frac{48}{11}}\)\(=\frac{9\left(1+\frac{1}{11}+\frac{2}{23}-\frac{3}{37}\right)}{8\left(1+\frac{1}{11}+\frac{2}{23}-\frac{3}{37}\right)}-\frac{2\left(1+\frac{8}{29}-\frac{12}{13}-\frac{16}{11}\right)}{3\left(1+\frac{8}{29}-\frac{12}{13}-\frac{16}{11}\right)}\)
\(=\frac{9}{8}-\frac{2}{3}\)(do \(1+\frac{1}{11}+\frac{2}{23}-\frac{3}{37};1+\frac{8}{29}-\frac{12}{13}-\frac{16}{11}\ne0\))
\(=\frac{27}{24}-\frac{16}{24}=\frac{11}{24}.\)
Vậy A = \(\frac{11}{24}.\)
Rut gon: \(A=\frac{9+\frac{9}{11}+\frac{18}{23}-\frac{27}{27}}{8+\frac{8}{11}+\frac{16}{23}-\frac{24}{37}}-\frac{2+\frac{16}{29}-\frac{24}{13}-\frac{32}{11}}{3+\frac{24}{29}-\frac{36}{13}-\frac{48}{11}}\)
Tìm S:
1/S=-1+3-5+7-...-53+55
2/2-5+8-11+...+-29+32
3/S=-1+5-9+13-...-41+45
4/S=1-5+9-13+...-89+93
5/S= -x+3y-4z , với y=2x-5 ; z=3y+8
1/S=-1+3-5+7-....-53+55
Có số cặp là :[(55-1)/2+1]/2=14
Mà khoảng cách giữa 2 số liền nhau là:-1+3=2;-5+7=2;.....
=>S=14*2=28(số cặp nhân với khoảng cách giữa 2 số)
2/S=2-5+8-11+....-29+32
Có số cặp là:5 dư 32
Mà khoảng cách giữa 2 số liền nhau là:2-5=-3;8-11=-3;....
=>S=[5*(-3)]+32=17
3/-1+5-9+13-....-41+45
Có số cặp là:[(45-1)/4+1]/2=6
Mà khoảng cách giữa 2 số liền nhau là:-1+5=4;-9+13=4;.....
=>S=6*4=24
4/S=1-5+9-13-...-41+45
Có số cặp là:[(45-1)/4+1]/2=6
Mà khoảng cách giữa 2 số là:1-5=-4;9-13=-4;...
=>S=6*(-4)=-24
Còn câu 5 mk ko biết làm nha!
1. \(S=-1+3-5+7-...-53+55\)
Số cặp là \(13\)
Mà \(3-5=-2\)
\(\Rightarrow S=-1+-2+...+-2+55\)
\(\Rightarrow S=-1+\left(-25\right)+55\)
\(\Rightarrow S=-27+55\)
\(\Rightarrow S=28\)
a,2/9-5/7+20/33+8/21+5/18-6/22
b, 1/2+1/3-1/4+1/6+1/8+1/16+1/32+1/64+1/128
c,5-1/2-5/6-11/12-19/20-29/30
các bn giúp mk nha