\(\dfrac{12}{26}\)+ \(\dfrac{12}{39}\)+ \(\dfrac{12}{52}\)
Rút gọn các phân số sau: a) \(\dfrac{-21}{28}\); \(\dfrac{-39}{52}\); \(\dfrac{-24}{63}\); \(\dfrac{12}{-21}\) b, \(\dfrac{-270}{450}\); \(\dfrac{11}{-143}\); \(\dfrac{-132}{156}\); \(\dfrac{-26}{169}\)
thực hiện phép tính
a) \(\dfrac{9}{18}-\dfrac{-7}{12}+\dfrac{13}{32}\) b) \(\dfrac{5}{-8}+\dfrac{14}{39}-\dfrac{6}{10}\) c) \(\dfrac{11}{26}+\dfrac{32}{39}-\dfrac{-14}{52}\)
help me!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
a, \(\dfrac{9}{18}-\dfrac{-7}{12}+\dfrac{13}{32}\)
\(=\dfrac{1}{2}+\dfrac{7}{12}+\dfrac{13}{32}\)
\(=\dfrac{13}{12}+\dfrac{13}{32}=\dfrac{143}{96}\)
b, \(\dfrac{5}{-8}+\dfrac{14}{39}-\dfrac{6}{10}\)
\(\dfrac{-5}{8}+\dfrac{14}{39}-\dfrac{3}{5}\)
\(=\dfrac{-5}{8}-\dfrac{3}{5}+\dfrac{14}{39}\)
\(=\dfrac{-49}{40}+\dfrac{14}{39}=\dfrac{-1351}{1560}\)
\(\dfrac{39}{x+2}=\dfrac{26}{12}\)
x = ?
\(\dfrac{39}{x+2}=\dfrac{26}{12}\\ \Rightarrow26\times\left(x+2\right)=39\times12\\ \Rightarrow26\times\left(x+2\right)=468\\ \Rightarrow x+2=468:26\\ \Rightarrow x+2=18\\ \Rightarrow x=18-2\\ \Rightarrow x=16\)
Bài 1:So Sánh(nhanh nhất)
\(\dfrac{-13}{38}va\dfrac{29}{-88},\dfrac{-18}{31}va\dfrac{-1818}{3131}\)
Bài 2:Tính
a)\(\dfrac{-1}{39}+\dfrac{-1}{52}\)
b)\(\dfrac{-6}{9}+\dfrac{-12}{16}\)
Bài 1:
\(\dfrac{-13}{38}\) và \(\dfrac{29}{-88}\)
\(\dfrac{-13}{38}=\dfrac{-13.29}{38.29}=\dfrac{-377}{1102}\)
\(\dfrac{29}{-88}=\dfrac{-29}{88}=\dfrac{-29.13}{88.13}=\dfrac{-377}{1144}\)
Vì \(\dfrac{-377}{1102}< \dfrac{-377}{1144}\) nên \(\dfrac{-13}{38}< \dfrac{29}{-88}\)
\(\dfrac{-18}{31}\) và \(\dfrac{-1818}{3131}\)
\(\dfrac{-18}{31}\)
\(\dfrac{-1818}{3131}=\dfrac{-1818:101}{3131:101}=\dfrac{-18}{31}\)
Vì \(\dfrac{-18}{31}=\dfrac{-18}{31}\) nên \(\dfrac{-18}{31}=\dfrac{-1818}{3131}\)
Bài 2:
a) \(\dfrac{-1}{39}+\dfrac{-1}{52}=\dfrac{-4}{156}+\dfrac{-3}{156}=\dfrac{-4+-3}{156}=\dfrac{-7}{156}\)
b) \(\dfrac{-6}{9}+\dfrac{-12}{16}=\dfrac{-2}{3}+\dfrac{-3}{4}=\dfrac{-8}{12}+\dfrac{-9}{12}=\dfrac{-17}{12}\)
10.Trong các phân số sau: \(\dfrac{15}{3}\);\(\dfrac{24}{42}\);\(\dfrac{0}{8}\);\(\dfrac{20}{12}\);\(\dfrac{15}{15}\);\(\dfrac{26}{39}\):
a) Phân số bằng \(\dfrac{5}{3}\) là: ... b) Phân số bằng 1 là: ... c) Phân số bằng \(\dfrac{4}{7}\) là: ...
d) Phân số bằng \(\dfrac{2}{3}\) là: ... c) Phân số bằng 0 là: ... d) Phân số bằng 5 là: ...
ghi mỗi kết quả thui nha k cần ghi đầy đủ đâu :)
a) \(\dfrac{20}{12}\) b) \(\dfrac{15}{15}\) c) \(\dfrac{24}{42}\)
d) \(\dfrac{26}{39}\) e) \(\dfrac{0}{8}\) g) \(\dfrac{15}{3}\)
a) \(\dfrac{15}{3}\)
b)\(\dfrac{15}{15}\)
c) \(\dfrac{24}{42}\)
d) \(\dfrac{26}{39}\)
e)\(\dfrac{0}{8}\)
f) \(\dfrac{15}{15}\)
9 - 3 x ( X - 9 ) = 6
4 + 6 x ( X + 1 ) 70
\(\dfrac{X}{13}+\dfrac{15}{26}=\dfrac{46}{52}\)
\(\dfrac{11}{14}-\dfrac{3}{X}=\dfrac{5}{14}\)
5 x ( 3 + 7 x X ) = 40
X x 6 + 12 : 3 = 120
X x 3,7 + X x 6,3 = 120
( 15 x 24 - X ) : 0,25 = 100 : \(\dfrac{1}{4}\)
71 + 65 x 4 = \(\dfrac{X+140}{X}\)+ 260
( X +1 ) + ( X + 4 ) + ( x + 7 ) + ...... + (X + 28 ) = 155
đây là bài tìm X
Giải:
\(9-3\times\left(x-9\right)=6\)
\(3\times\left(x-9\right)=9-6\)
\(3\times\left(x-9\right)=3\)
\(x-9=3:3\)
\(x-9=1\)
\(x=1+9\)
\(x=10\)
\(4+6\times\left(x+1\right)=70\)
\(6\times\left(x+1\right)=70-4\)
\(6\times\left(x+1\right)=66\)
\(x+1=66:6\)
\(x+1=11\)
\(x=11-1\)
\(x=10\)
\(\dfrac{x}{13}+\dfrac{15}{26}=\dfrac{46}{52}\)
\(\dfrac{x}{13}=\dfrac{23}{26}-\dfrac{15}{26}\)
\(\dfrac{x}{13}=\dfrac{4}{13}\)
\(\Rightarrow x=4\)
\(\dfrac{11}{14}-\dfrac{3}{x}=\dfrac{5}{14}\)
\(\dfrac{3}{x}=\dfrac{11}{14}-\dfrac{5}{14}\)
\(\dfrac{3}{x}=\dfrac{3}{7}\)
\(\Rightarrow x=7\)
\(5\times\left(3+7\times x\right)=40\)
\(3+7\times x=40:5\)
\(3+7\times x=8\)
\(7\times x=8-3\)
\(7\times x=5\)
\(x=5:7\)
\(x=\dfrac{5}{7}\)
\(x\times6+12:3=120\)
\(x\times6+4=120\)
\(x\times6=120-4\)
\(x\times6=116\)
\(x=116:6\)
\(x=\dfrac{58}{3}\)
\(x\times3,7+x\times6,3=120\)
\(x\times\left(3,7+6,3\right)=120\)
\(x\times10=120\)
\(x=120:10\)
\(x=12\)
\(\left(15\times24-x\right):0,25=100:\dfrac{1}{4}\)
\(\left(360-x\right):0,25=400\)
\(360-x=400.0,25\)
\(360-x=100\)
\(x=360-100\)
\(x=260\)
\(71+65\times4=\dfrac{x+140}{x}+260\)
\(\left(x+140\right):x+260=71+260\)
\(x:x+140:x+260=331\)
\(1+140:x+260=331\)
\(140:x=331-1-260\)
\(140:x=70\)
\(x=140:70\)
\(x=2\)
\(\left(x+1\right)+\left(x+4\right)+\left(x+7\right)+...+\left(x+28\right)=155\)
\(10\times x+\left(1+4+7+...+28\right)=155\)
Số số hạng \(\left(1+4+7+...+28\right)\) :
\(\left(28-1\right):3+1=10\)
Tổng dãy \(\left(1+4+7+...+28\right)\) :
\(\left(1+28\right).10:2=145\)
\(\Rightarrow10\times x+145=155\)
\(10\times x=155-145\)
\(10\times x=10\)
\(x=10:10\)
\(x=1\)
Đều theo cách lớp 5 nha em!
bài 1)
a)(\(\dfrac{12}{42}\) - \(\dfrac{26}{91}\) ).(\(\dfrac{-4}{7}\) +\(\dfrac{-5}{9}\))
b) \(\dfrac{9}{13}\) . \(\dfrac{-12}{7}\) +\(\dfrac{9}{13}\) .\(\dfrac{29}{17}\)
c) \(\dfrac{4}{7}\) +\(\dfrac{6}{7}\) .\(\dfrac{1}{7}\) +\(\dfrac{1}{7}\) .\(\dfrac{8}{7}\)
d) (\(\dfrac{5}{7}\) + \(\dfrac{9}{7}\) ). \(\dfrac{7}{10}\) +(\(\dfrac{8}{7}\) + \(\dfrac{13}{7}\) ). \(\dfrac{7}{10}\)
a: =(2/7-2/7)(-4/7-5/9)=0
b:
Sửa đề: 9/13*(-12/17)+9/13*29/27
=9/13(-12/17+29/17)
=9/13*17/17=9/13
c: \(=\dfrac{1}{7}\left(4+\dfrac{6}{7}+\dfrac{8}{7}\right)=\dfrac{1}{7}\cdot6=\dfrac{6}{7}\)
d: =7/10(5/7+9/7+8/7+13/7)
=5*7/10=7/2
a)\(\dfrac{-12}{15}+\dfrac{-4}{26}\) b)\(5\dfrac{1}{3}-2\dfrac{4}{5}\)
c)\(\dfrac{4}{5}-\left(-\dfrac{2}{7}\right)+-\dfrac{5}{10}\) d)\(-1\dfrac{2}{7}+\dfrac{3}{14}-\dfrac{5}{21}\)
e)\(12-\dfrac{11}{121}+\left(-\dfrac{8}{9}\right)-\left(-\dfrac{3}{7}\right)\) f) \(\dfrac{11}{12}-\left(1\dfrac{3}{4}\right)-\dfrac{2}{16}\)
a) \(\dfrac{-12}{15}+\dfrac{-4}{26}=\dfrac{-4}{5}+\dfrac{-2}{13}=\dfrac{-52-10}{65}=\dfrac{-62}{65}\)
b) \(5\dfrac{1}{3}-2\dfrac{4}{5}=\dfrac{16}{3}-\dfrac{14}{5}=\dfrac{80}{15}-\dfrac{42}{15}=\dfrac{38}{15}\)
c) \(\dfrac{4}{5}-\left(-\dfrac{2}{7}\right)+\dfrac{-5}{10}=\dfrac{4}{5}+\dfrac{2}{7}-\dfrac{1}{2}=\dfrac{56}{70}+\dfrac{20}{70}-\dfrac{35}{70}=\dfrac{41}{70}\)
d) \(-1\dfrac{2}{7}+\dfrac{3}{14}-\dfrac{5}{21}=\dfrac{-9}{7}+\dfrac{3}{14}-\dfrac{5}{21}=\dfrac{-54}{42}+\dfrac{9}{42}-\dfrac{10}{42}=\dfrac{-55}{42}\)
e) \(12-\dfrac{11}{121}+\left(\dfrac{-8}{9}\right)-\left(-\dfrac{3}{7}\right)\)
\(=12-\dfrac{11}{121}-\dfrac{8}{9}+\dfrac{3}{7}\)
\(=\dfrac{91476}{7623}-\dfrac{693}{7623}-\dfrac{6776}{7623}+\dfrac{3267}{7623}\)
\(=\dfrac{7934}{693}\)
CMR:\(\dfrac{7}{12}< \dfrac{1}{51}+\dfrac{1}{52}+...+\dfrac{1}{100}< \dfrac{5}{6}\)
giúp mk nhé
Đặt \(A=\dfrac{1}{51}+\dfrac{1}{52}+...+\dfrac{1}{100}\)
Ta có: \(\dfrac{1}{51}+\dfrac{1}{52}+...+\dfrac{1}{75}>\dfrac{1}{75}+\dfrac{1}{75}+...+\dfrac{1}{75}=\dfrac{25}{75}=\dfrac{1}{3}\)
\(\dfrac{1}{76}+\dfrac{1}{77}+...+\dfrac{1}{100}>\dfrac{1}{100}+\dfrac{1}{100}+...+\dfrac{1}{100}=\dfrac{25}{100}=\dfrac{1}{4}\)
Do đó: \(A>\dfrac{1}{3}+\dfrac{1}{4}=\dfrac{7}{12}\)(1)
Ta có: \(\dfrac{1}{51}+\dfrac{1}{52}+...+\dfrac{1}{75}< \dfrac{1}{50}+\dfrac{1}{50}+...+\dfrac{1}{50}=\dfrac{25}{50}=\dfrac{1}{2}\)
\(\dfrac{1}{76}+\dfrac{1}{77}+...+\dfrac{1}{100}< \dfrac{1}{75}+\dfrac{1}{75}+...+\dfrac{1}{75}=\dfrac{25}{75}=\dfrac{1}{3}\)
Do đó: \(A< \dfrac{1}{2}+\dfrac{1}{3}=\dfrac{5}{6}\)(2)
Từ (1) và (2) ta suy ra ĐPCM