2/5÷2/3=?
1/6÷1/3=?
4/7÷4/5=?
1/4÷1/8=?
Giúp mình nha😣😣😣
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a) \(-5x+\frac{1}{2}=\frac{2}{3}\\ -5x=\frac{2}{3}-\frac{1}{2}\\ -5x=\frac{1}{6}\\ x=\frac{1}{6}:\left(-5\right)\\ x=\frac{-1}{30}\)Vậy \(x=\frac{-1}{30}\)
b) \(\frac{1}{-5}-\frac{2}{3}+1\frac{1}{2}x=\frac{1}{2}\\ \frac{-13}{15}+\frac{3}{2}x=\frac{1}{2}\\ \frac{3}{2}x=\frac{1}{2}-\frac{-13}{15}\\ \frac{3}{2}x=\frac{41}{30}\\ x=\frac{41}{30}:\frac{3}{2}\\ x=\frac{41}{45}\)Vậy \(x=\frac{41}{45}\)
c) \(2\left(\frac{1}{4}-3x\right)=\frac{1}{5}-4x\\ \frac{1}{2}-6x=\frac{1}{5}-4x\\ \frac{1}{2}-\frac{1}{5}=6x-4x\\ \frac{3}{10}=2x\\ x=\frac{3}{10}:2\\ x=\frac{3}{20}\)Vậy \(x=\frac{3}{20}\)
d) \(\frac{-5}{2}-3\left(\frac{1}{3}-x\right)=\frac{1}{4}-7x\\ \frac{-5}{2}-1+3x=\frac{1}{4}-7x\\ \frac{-7}{2}+3x=\frac{1}{4}-7x\\ 7x+3x=\frac{1}{4}+\frac{7}{2}\\ 10x=\frac{15}{4}\\ x=\frac{15}{4}:10\\ x=\frac{3}{8}\)Vậy \(x=\frac{3}{8}\)
\(\frac{2}{7}+\frac{7}{12}=\frac{24}{84}+\frac{49}{84}=\frac{73}{84}\)
\(\frac{25}{48}+\frac{22}{48}=\frac{47}{48}\)
\(\frac{5}{7}+\frac{3}{8}=\frac{40}{56}+\frac{21}{56}=\frac{61}{56}\)
\(\frac{15}{24}+\frac{15}{16}=15.\left(\frac{1}{24}+\frac{1}{16}\right)=\frac{25}{16}\)
\(\frac{5}{6}+\frac{3}{4}=\frac{20+18}{24}=\frac{19}{12}\)
\(\frac{9}{24}+\frac{14}{24}=\frac{23}{24}\)
học tót tích mình hem
2) \(\left(x-5\right)\left(x^2+1\right)=0\)
\(\Rightarrow x-5=0\) vì \(x^2+1>0\)
\(\Rightarrow x=5\)
cAU 1 TƯƠNG TỰ NHÉ
Tương tự sao được
a/ \(30.\left\{x+2+6\left(x-5\right)\right\}-24x=102\)
\(\Leftrightarrow30.\left\{x+2+6x-30\right\}-24x=102\)
\(\Leftrightarrow30.\left\{7x-28\right\}-24x=102\)
\(\Leftrightarrow210x-340-24x=102\)
\(\Leftrightarrow186x-340=102\)
\(\Leftrightarrow186x=442\)
\(\Leftrightarrow x=\frac{442}{186}\)
c/ \(\left(x+1\right)+\left(x+2\right)+....+\left(x+99\right)=0\)
\(\Leftrightarrow\left(x+x+...+x\right)+\left(1+2+......+99\right)=0\)
\(\Leftrightarrow99x+49500=0\)
\(\Leftrightarrow x=-50\)
Bài 1 :
1) a2 - 4 + y ( a - 2 )
= ( a + 2 ) ( a - 2 ) + y ( a - 2 )
= ( a - 2 ) ( a + 2 + y )
2) ( x - 2 )2 - 9y2
= ( x - 2 - 3y ) ( x - 2 + 3y )
Bài 2 :
1) 3 ( x + 4 ) - 2x = 5
=> 3x + 12 - 2x = 5
=> x + 12 = 5
=> x = 5 - 12 = - 7
Vậy x = - 7
2) x ( x - 2 ) - x2 - 6 = 0
=> x2 - 2x - x2 - 6 = 0
=> - 2x - 6 = 0
=> 2x = - 6
=> x = \(-\frac{6}{2}=3\)
Vậy x = 3
3 ) x2 - 3x = 0
=> x ( x - 3 ) = 0
=> \(\orbr{\begin{cases}x=0\\x-3=0\end{cases}}\)
=> \(\orbr{\begin{cases}x=0\\x=3\end{cases}}\)
Vậy \(x\in\left\{0;3\right\}\)
4) 5 - 3 ( x - 6 ) = 4
=> 5 - 3x + 18 = 4
=> 3x = 5 + 18 - 4
=> 3x = 19
=> x = \(\frac{19}{3}\)
Vậy \(x=\frac{19}{3}\)
Ta có
\(\frac{1}{2}=\frac{1\times3\times5}{2\times3\times5}=\frac{15}{30}\)
\(\frac{1}{3}=\frac{1\times2\times5}{3\times2\times5}=\frac{10}{30}\)
\(\frac{2}{5}=\frac{2\times2\times3}{5\times2\times3}=\frac{12}{30}\)
Hok tốt !!!!!!!!!!!!!!!!!!!
a, 48
b, 21
Còn bài tính n bạn xem lại đề kết quả của tổng bằng mấy, ko có tổng ko làm đc bạn à
(x+1)+(x+2)+(x+3).........(x+1000)
=x+1+x+2+...+x+1000
=1000x+(1+2+3+...+1000)
=1000x+(1000-1+1).(1000+1):2=500500+1000x
\(\frac{2}{5}\)\(:\frac{2}{3}\)\(=\frac{6}{10}\)\(=\frac{3}{5}\)
\(\frac{1}{6}\)\(:\frac{1}{3}\)\(=\frac{3}{6}\)\(=\frac{1}{2}\)
\(\frac{4}{7}\)\(:\frac{4}{5}\)\(=\frac{20}{28}\)\(=\frac{5}{7}\)
\(\frac{1}{4}\)\(:\frac{1}{8}\)\(=\frac{8}{4}\)\(=2\)
2/5:2/3=3/5
1/6:1/3=1/2
4/7:4/5=5/7
1/4:1/8=2
HOK TỐT!