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Bài 1:
a) Ta có: \(\frac{-5}{7}+\frac{2}{7}+\frac{4}{-9}+\frac{4}{9}\)
\(=-\frac{3}{7}+\frac{-4}{9}+\frac{4}{9}\)
\(=-\frac{3}{7}\)
b) Ta có: \(\left(\frac{1}{2}:\frac{3}{4}\right)^2\)
\(=\left(\frac{1}{2}\cdot\frac{4}{3}\right)^2\)
\(=\left(\frac{2}{3}\right)^2=\frac{4}{9}\)
c) Ta có: \(\frac{1}{2}+\frac{3}{4}-\left(\frac{4}{5}+\frac{3}{4}\right)\)
\(=\frac{1}{2}+\frac{3}{4}-\frac{4}{5}-\frac{3}{4}\)
\(=\frac{1}{2}-\frac{4}{5}\)
\(=\frac{5}{10}-\frac{8}{10}=\frac{-3}{10}\)
d) Ta có: \(5^6:5^4+2^3\cdot2^2-225:15^2\)
\(=5^2+2^5-\frac{15^2}{15^2}\)
\(=25+32-1\)
\(=56\)
e) Ta có: \(\frac{7}{23}+\frac{4}{17}-\frac{7}{23}+\frac{13}{17}\)
\(=\frac{4}{17}+\frac{13}{17}\)
\(=\frac{17}{17}=1\)
g) Ta có: \(19\frac{1}{4}\cdot\frac{7}{12}-15\frac{1}{4}\cdot\frac{7}{12}\)
\(=\frac{7}{12}\left(19+\frac{1}{4}-15-\frac{1}{4}\right)\)
\(=\frac{7}{12}\cdot4=\frac{7}{3}\)
a
\(5\frac{4}{7}:x+=13\)
\(\frac{39}{7}:x=13\)
\(x=\frac{39}{7}:13\)
\(x=\frac{3}{7}\)
\(\frac{4}{7}x=\frac{9}{8}-0,125\)
\(\frac{4}{7}x=1\)
\(x=1:\frac{4}{7}\)
\(x=\frac{7}{4}=1\frac{3}{4}\)
câu 1 :
\(A=\frac{-7}{12}:\frac{49}{11}\cdot\frac{5}{121}-\frac{7}{6}\) \(B=\frac{1}{8}-\frac{8}{7}:8-3:\frac{3}{4}\cdot-2^3\)
\(A=\frac{-11}{84}\cdot\frac{5}{121}-\frac{7}{6}\) \(B=\frac{1}{8}-\frac{8}{7}:\frac{8}{1}-\frac{3}{1}:\frac{3}{4}\cdot\left(-2^3\right)\)
\(A=\frac{-5}{924}-\frac{7}{6}\) \(B=\frac{1}{8}-\frac{1}{7}-\left(-32\right)\)
\(A=\frac{-361}{308}\) \(B=\frac{-1}{56}-\left(-32\right)\)
\(B=\frac{1791}{56}\)
Câu 2 :
a)\(\frac{22}{7}:x=\frac{11}{7}\) b)\(\left(1-3x\right)\cdot\frac{4}{3}=-2^3\)
\(x=\frac{22}{7}:\frac{11}{7}\) \(\left(1-3x\right)\cdot\frac{4}{3}=-8\)
\(x=2\) \(\left(1-3x\right)=-8:\frac{4}{3}\)
\(\left(1-3x\right)=-6\)
\(3x=-6-1=7\)
\(3x=7:3=\frac{7}{3}\)
c ) bằng \(\frac{27}{5}\)nhé
\(C=\frac{3}{3.5}+\frac{3}{5.7}+......+\frac{3}{47.49}\)
\(=\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+.....+\frac{1}{47}-\frac{1}{49}\)
\(=\frac{1}{3}-\frac{1}{49}\)
a)
C = \(\frac{3}{3.5}+\frac{3}{5.7}+\frac{3}{7.9}+........+\frac{3}{47.49}\)
C = \(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+\frac{1}{9}-.........-\frac{1}{47}+\frac{1}{47}-\frac{1}{49}\)
C = \(\frac{1}{3}-\frac{1}{49}\)
C = \(\frac{49}{147}-\frac{3}{147}\)
C = \(\frac{46}{147}\)
b) \(\frac{7}{2}.\left(\frac{1}{2}-x\right)-\frac{1}{8}=\frac{3}{4}\)
\(\frac{7}{2}.\left(\frac{1}{2}-x\right)=\frac{3}{4}+\frac{1}{8}\)
\(\frac{7}{2}.\left(\frac{1}{2}-x\right)=\frac{24}{32}+\frac{4}{32}\)
\(\frac{7}{2}.\left(\frac{1}{2}-x\right)=\frac{28}{32}\)
\(\frac{1}{2}-x=\frac{28}{32}:\frac{7}{2}\)
\(\frac{1}{2}-x=\frac{7}{8}.\frac{2}{7}\)
\(\frac{1}{2}-x=\frac{1}{4}\)
\(x=\frac{1}{2}-\frac{1}{4}\)
\(x=\frac{2}{4}-\frac{1}{4}=\frac{1}{4}\)
Vậy x = \(\frac{1}{4}\)
\(a.-1,52+\frac{2}{47}-x=3.\)
\(\Leftrightarrow\frac{2}{47}-x=4,52\)
\(\Leftrightarrow x=\frac{2}{47}-4,52\)
\(\Leftrightarrow x=-\frac{5261}{1175}\)
\(b.x+3,5-\frac{4}{7}=\frac{3}{2}-1\frac{3}{5}\)
\(\Leftrightarrow x=\frac{3}{2}-\frac{8}{5}-\frac{7}{2}+\frac{4}{7}\)
\(\Leftrightarrow x=-\frac{106}{35}\)
\(c.\left(x:2\frac{1}{8}\right).\frac{1}{6}=-\frac{3}{8}.\left(\frac{1}{2}-1\frac{3}{5}\right)\)
\(\Leftrightarrow\left(x:\frac{17}{8}\right).\frac{1}{6}=-\frac{3}{16}+\frac{3}{5}\)
\(\Leftrightarrow\left(x:\frac{17}{8}\right).\frac{1}{6}=\frac{33}{80}\)
\(\Leftrightarrow x:\frac{17}{8}=\frac{99}{40}\)
\(\Leftrightarrow x=\frac{99}{40}.\frac{17}{8}\)
\(\Leftrightarrow x=\frac{1683}{320}\)
Bài 2:
b: x+25%x=-1,25
=>1,25x=-1,25
hay x=-1
c: x-75%x=1/4
=>1/4x=1/4
hay x=1
Bài 2:
a: =3/2-11/4=6/4-11/4=-5/4
b: =-49/6-17/2=-49/6-51/6=-100/6=-50/3
a) \(1\frac{5}{8}:x-1\frac{1}{4}=2\)
=> \(\frac{13}{8}:x-\frac{5}{4}=2\)
=> \(\frac{13}{8}:x=\frac{13}{4}\)
=> \(x=\frac{13}{8}:\frac{13}{4}=\frac{13}{8}\cdot\frac{4}{13}=\frac{1}{2}\)
b) \(\left(x-\frac{1}{3}\right)^2-\frac{1}{2}=0\)
=> \(\left(x-\frac{1}{3}\right)^2=\frac{1}{2}\)
=> x không thỏa mãn
c) 2(x - 1) = 3x + 1
=> 2x - 2 = 3x + 1
=> 2x - 2 - 3x - 1 = 0
=> 2x - 3x - 2 - 1 = 0
=> -x = 3
=> x = -3
d) \(\frac{-2}{x}=\frac{x}{-8}\)=> x2 = 16 => x = \(\pm\)4
e) |7 - x| + 2x = 11
=> |7 - x| = 11 - 2x
=> 7 - x = 11 - 2x
=> 7 - x - 11 + 2x = 0
=> 7 - 11 - x + 2x = 0
=> -4 + x = 0
=> -4 = -x
=> x = 4
a)=> 13/8 : x-5/4 =2
<=> 13/8 : x= 13/4
<=> x=1/2
b)=>x2 - (1/3)2 = 1/2
=>x2-1/9=1/2
=>x2=11/18
=>x=0.78 (bằng xấp xỉ thôi nhé bạn :33)
c)=>2x-2=3x-1
=>2x-3x=2-1
=>-x=1
=>x=-1
còn 2 câu bạn làm nốt nhé :33
k đúng cho mk nhé!!!!
(1/8).4/3-2/7.12,25
=1/6-7/2=-10/3
\(\left(\frac{7}{8}-\frac{3}{4}\right)\cdot1\frac{1}{3}-\frac{2}{7}\cdot\left(3,5\right)^2\)\(=\frac{1}{8}\cdot\frac{4}{3}-\frac{2}{7}\cdot12,25\)\(=\frac{1}{6}-3,5=\frac{1}{6}-\frac{7}{5}=\frac{-37}{30}\)