A)5-1/3-4,5=
B)2- 3/5-4/5=
C)2/+1-4/5=
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a, 2x+ 1/4 = 3/2
2x = 3/2-1/4
2x = 5/4
x=5/4:2
x= 5/8
b, (x-5) - 1/3 = 2/5
x-5= 2/5+1/3
x-5=11/15
x=11/15+5
x=86/15
c, (4,5-2x):3/4=4/3
(4,5-2x)=4/3. 3/4
4,5-2x=1
2x= 5,5
x=5,5:2
x=2,75
a) 2x+1/4=3/2
=> 2x =3/2-1/4
=> 2x =5/4
=> x =5/4:2
=> x =5/8
b) (x-5)-1/3=2/5
=> x-5 =2/5+1/3
=> x-5 =11/15
=> x =11/15+5
=> x =86/15
c) (4,5-2x):3/4=4/3
=> 4,5-2x =4/3x3/4
=> 4,5-2x =1
=> 2x =4,5-1
=> 2x =3,5
=> x =3,5:2
=> x =1,75
a: Ta có: \(\left|\dfrac{2}{5}-x\right|+\dfrac{1}{2}=3.5\)
\(\Leftrightarrow\left|x-\dfrac{2}{5}\right|=3\)
\(\Leftrightarrow\left[{}\begin{matrix}x-\dfrac{2}{5}=3\\x-\dfrac{2}{5}=-3\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{17}{5}\\x=-\dfrac{13}{5}\end{matrix}\right.\)
b: Ta có: \(\dfrac{21}{5}+3:\left|\dfrac{x}{4}-\dfrac{2}{3}\right|=6\)
\(\Leftrightarrow3:\left|\dfrac{1}{4}x-\dfrac{2}{3}\right|=6-\dfrac{21}{5}=\dfrac{9}{5}\)
\(\Leftrightarrow\left|\dfrac{1}{4}x-\dfrac{2}{3}\right|=\dfrac{5}{3}\)
\(\Leftrightarrow\left[{}\begin{matrix}\dfrac{1}{4}x-\dfrac{2}{3}=\dfrac{5}{3}\\\dfrac{1}{4}x-\dfrac{2}{3}=-\dfrac{5}{3}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}\dfrac{1}{4}x=\dfrac{7}{3}\\\dfrac{1}{4}x=-1\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{28}{3}\\x=-4\end{matrix}\right.\)
em muốn hỏi là tại sao 3,5 bên trên xuống dưới lại là 3 và -x +2/5 của em xuống dưới lại chuyển thành x-2/5 ạ mong anh giải đáp
a) Ta có: \(\frac{4}{5}+x=\frac{2}{3}\)
hay \(x=\frac{2}{3}-\frac{4}{5}=\frac{10}{15}-\frac{12}{15}=\frac{-2}{15}\)
Vậy: \(x=\frac{-2}{15}\)
b) Ta có: \(\frac{3}{4}-x=\frac{1}{3}\)
hay \(x=\frac{3}{4}-\frac{1}{3}=\frac{9}{12}-\frac{4}{12}=\frac{5}{12}\)
Vậy: \(x=\frac{5}{12}\)
c) Ta có: \(x-\frac{5}{9}=\frac{-2}{3}\)
hay \(x=\frac{-2}{3}+\frac{5}{9}=\frac{-6}{9}+\frac{5}{9}=-\frac{1}{9}\)
Vậy: \(x=\frac{-1}{9}\)
d) Ta có: \(\frac{\left(4,5-2x\right)}{\frac{3}{4}}=1\frac{1}{3}\)
\(\Leftrightarrow\frac{9}{2}-2x=\frac{4}{3}\cdot\frac{3}{4}=1\)
\(\Leftrightarrow2x=\frac{9}{2}-1=\frac{7}{2}\)
hay \(x=\frac{7}{4}\)
Vậy: \(x=\frac{7}{4}\)
\(a.\dfrac{5}{3}.8,1=\dfrac{40,5}{3}\)
\(b.\dfrac{8}{5}.\left(-4,5\right)=\dfrac{-36}{5}\)
\(c.\dfrac{14}{5}.75\%=\dfrac{10,5}{5}=2,1\)
\(d.\dfrac{11}{8}.\dfrac{37}{12}=\dfrac{407}{96}\)
1.
a) \(\frac{-7}{9}.2\frac{3}{4}=\frac{-7}{9}.\frac{11}{4}=\frac{-77}{36}\)
b) \(\frac{2}{3}+\frac{1}{3}.\frac{-2}{5}=\frac{2}{3}+\frac{-2}{15}=\frac{8}{15}\)
c) \(\frac{3}{4}.15\frac{1}{3}-\frac{3}{4}.43\frac{1}{3}=\frac{3}{4}.\frac{46}{3}-\frac{3}{4}.\frac{130}{3}=\frac{23}{2}-\frac{65}{2}=-21\)
d) \(\left(-49,1\right).\frac{13}{27}-58,9.\frac{13}{27}=\frac{13}{27}.\left(-49,1-58,9\right)=\frac{13}{27}.\left(-108\right)=-52\)
e) \(0,375:\left(-4,5\right)=\frac{-1}{12}\)
f) \(3\frac{1}{7}:\left(-1\frac{3}{7}\right)=\frac{22}{7}:\frac{-10}{7}=\frac{-11}{5}\)
g) \(9\frac{1}{3}:4\frac{2}{3}-2=\frac{28}{3}:\frac{14}{3}-2=2-2=0\)
h) \(\left(7\frac{3}{4}:0,3125+4,5.2\frac{2}{45}\right):\left(-8,5\right)=\left(\frac{31}{4}:\frac{5}{16}+\frac{9}{2}.\frac{92}{45}\right):\frac{-17}{2}=\left(\frac{124}{5}+\frac{46}{5}\right):\frac{-17}{2}=34:\frac{-17}{2}=-4\)
Bài 1 : Tính:
a)
\(\frac{-7}{9}.2\frac{3}{4}=\frac{-7}{9}.\frac{11}{4}=\frac{-77}{36}\)
b)
\(\frac{2}{3}+\frac{1}{3}.\frac{-2}{5}=\frac{2}{3}+\frac{-2}{15}=\frac{10}{15}+\frac{-2}{15}=\frac{8}{15}\)
c)
\(\frac{3}{4}.15\frac{1}{3}-\frac{3}{4}.43\frac{1}{3}=\frac{3}{4}.\frac{46}{3}-\frac{3}{4}.\frac{130}{3}\)\(=\frac{23}{2}-\frac{65}{2}=\frac{-42}{2}=-21\)
....
Tự lm tiếp dạng như v
Bài 2 :
\(A=\frac{-6}{11}.\frac{7}{10}.\frac{11}{-6}.-20=\left(\frac{-6}{11}.\frac{11}{-6}\right).\left(\frac{7}{10}.-20\right)\)\(=1.\left(-14\right)=-14\)
.....
Bài 3 :
\(\frac{3}{7}.x-\frac{2}{5}.x=\frac{-17}{35}\)
\(\Leftrightarrow\frac{3}{7}-\frac{2}{5}.x=\frac{-17}{35}\)
\(\Leftrightarrow\frac{1}{35}x=\frac{-17}{35}\)
\(\Leftrightarrow x=\frac{-17}{35}:\frac{1}{35}\)
\(\Leftrightarrow x=\frac{-17}{35}.35=-17\)
Câu c là 2/5+1-4/5=
5-1/3-4/5=58/15
2-3/5-4/5=3/5
2+1-4/5=11/5