Tìm x, biết:
a ) 4 3 . x = 2 5 b ) x . 3 7 = 21 5 ; c ) 4 9 + 5 6 : x = 1 6 d ) 5 4 : x + 2 = 2 3
K
Khách
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
Những câu hỏi liên quan
KM
2
5 tháng 7 2018
a. 3/7 - 1/2x = 5/3
=> 1/2x = 3/7 - 5/3
=> 1/2x = 9/21 - 15/21
=> 1/2x = -26/21
=> x = -26/21 : 1/2
=> x = -26/21.2
=> x = -52/21
b. -2x + 3/14 = 1/7 - 4/21
=> -2x = -3/14 + 1/7 - 4/21
=> -2x = -18/84 + 12/84 - 16/84
=> -2x = -22/84
=> x = -22/84 : -2
=> x = -22/84 . (-1/2)
=> x = 11/84
BT
5 tháng 7 2018
a. 3/7 - 1/2x = 5/3
=> 1/2x = 3/7 - 5/3
=> 1/2x = 9/21 - 15/21
=> 1/2x = -26/21
=> x = -26/21 : 1/2
=> x = -26/21.2
=> x = -52/21
b. -2x + 3/14 = 1/7 - 4/21
=> -2x = -3/14 + 1/7 - 4/21
=> -2x = -18/84 + 12/84 - 16/84
=> -2x = -22/84
=> x = -22/84 : -2
=> x = -22/84 . (-1/2)
=> x = 11/84
5 tháng 6 2018
Bài 1:
a) \(\frac{16}{15}.\frac{\left(-5\right)}{14}.\frac{54}{24}.\frac{56}{21}\)
\(=\frac{4.2.2}{5.3}.\frac{\left(-5\right)}{2.7}.\frac{3.3}{4}.\frac{8}{3}\)
\(=\frac{4.2.2.\left(-5\right).3.3.8}{5.3.2.7.4.3}\)
\(=\frac{-16}{7}\)
b) \(\frac{7}{3}.\frac{\left(-5\right)}{2}.\frac{15}{21}.\frac{4}{\left(-5\right)}\)
\(=\frac{7}{3}.\frac{\left(-5\right)}{2}.\frac{5}{7}.\frac{2.2}{\left(-5\right)}\)
\(=\frac{7.\left(-5\right).5.2.2}{3.2.7.\left(-5\right)}\)
\(=\frac{10}{3}\)
5 tháng 6 2018
Bài 2:
a) \(\frac{21}{24}.\frac{11}{9}.\frac{5}{7}=\frac{7}{8}.\frac{11}{9}.\frac{5}{7}=\frac{11.5}{8.9}=\frac{55}{72}\)
b) \(\frac{5}{23}.\frac{17}{26}+\frac{5}{23}.\frac{9}{26}\)
\(=\frac{5}{23}.\left(\frac{17}{26}+\frac{9}{26}\right)=\frac{5}{23}.1=\frac{5}{23}\)
c) \(\left(\frac{3}{29}-\frac{1}{5}\right).\frac{29}{3}=\frac{3}{29}.\frac{29}{3}-\frac{1}{5}.\frac{29}{3}\)
\(=1-1\frac{14}{15}=\frac{14}{15}\)
Bài 3:
a) x/5 = 2/5
=> x =2
b) -4/x = 20/14 = 10/7
=> -4/x = 10/7
=> x.10 = (-4).7
x.10 = - 28
x= -28 :10
x= -2,8
c) 4/7 = 12/x = 12/ 21
=> 12/x = 12/21
=> x = 21
d) 3/7 = x / 21 = 9/21
=> x/21 = 9/21
=> x= 9
ML
30 tháng 5 2023
a/
\(\Leftrightarrow A=\dfrac{3}{8}xy^2+B-\dfrac{5}{6}x^2y+\dfrac{3}{4}x^2y-\dfrac{5}{8}xy^2\\ \Leftrightarrow A-B=-\dfrac{1}{12}x^2y-\dfrac{1}{4}xy^2\)
b/
\(\Leftrightarrow A-B=5xy^3-\dfrac{5}{8}yx^3-\dfrac{21}{4}xy^3+\dfrac{3}{7}x^3y\\ \Leftrightarrow A-B=-\dfrac{1}{4}xy^3-\dfrac{11}{56}x^3y\)
2 tháng 4 2016
làm mẫu nhé:
a) /4/5 - 1/5x/ - 2/3 = 1/5
=> /4/5 - 1/5x/ = 1/5 + 2/3 = 13/15
=> /4/5 - 1/5x/ = 13/15
/ 4/5 - 1/5x / = -13/15
=> 1/5x = 4/5 - 13/15 = -1/15 => x = -1/15 : 1/5 = -1/3
=> 1/5x = 4/5 - (-13/15) = 5/3 => x = 5/3 : 1/5 = 25/3
còn lại tương tự nha
KV
5 tháng 5 2023
a) 2/3 x + 1/2 = 1/10
2/3 x = 1/10 - 1/2
2/3 x = -2/5
x = -2/5 : 2/3
x = -3/5
b) 2/3 x + 1/5 = 7/10
2/3 x = 7/10 - 1/5
2/3 x = 1/2
x = 1/2 : 2/3
x = 3/4
c) (3 4/5 - 2x) . 1 1/3 = 5
19/5 - 2x = 5 : 4/3
19/5 - 2x = 15/4
2x = 19/5 - 15/4
2x = 1/20
x = 1/20 : 2
x = 1/40
d) x/7 = 6/(-21)
x = 6.7/(-21)
x = -2
30 tháng 6 2018
a) | 5/4x -7/2| - | 5/8x + 3/5| = 0
|5/4x - 7/2| = | 5/8x + 3/5|
TH1: 5/4x - 7/2 = 5/8x + 3/5
=> 5/4x - 5/8x = 3/5 +7/2
5/8x = 41/10
x = 41/10:5/8
x = 164/25
TH2: 5/4x - 7/2 = -5/8x - 3/5
=> 5/4x + 5/8x = -3/5 +7/2
15/8x = 29/10
x = 29/10 : 15/8
x = 116/75
KL: x = 164/25 hoặc x = 116/75
các bài cn lại b lm tương tự nha! h lm dài lắm!
NT
Nguyễn Thị Thương Hoài
Giáo viên
VIP
18 tháng 9 2023
a, \(\dfrac{3}{7}\)\(x\)- \(\dfrac{2}{3}\)\(x\) = \(\dfrac{10}{21}\)
(\(\dfrac{3}{7}\) - \(\dfrac{2}{3}\)) \(\times\) \(x\) = \(\dfrac{10}{21}\)
- \(\dfrac{5}{21}\) \(\times\) \(x\) = \(\dfrac{10}{21}\)
\(x\) = \(\dfrac{10}{21}\) : (-\(\dfrac{5}{21}\))
\(x\) = -2
b, \(\dfrac{7}{35}\) : (\(x-\dfrac{1}{3}\)) = - \(\dfrac{2}{25}\)
\(x\) - \(\dfrac{1}{3}\) = \(\dfrac{7}{35}\) : (- \(\dfrac{2}{25}\))
\(x\) - \(\dfrac{1}{3}\) = - \(\dfrac{5}{2}\)
\(x\) = - \(\dfrac{5}{2}\) + \(\dfrac{1}{3}\)
\(x\) = - \(\dfrac{13}{6}\)
c, 3.(\(x\) - \(\dfrac{1}{2}\)) - 5.(\(x\) + \(\dfrac{3}{5}\)) = - \(x\)+ \(\dfrac{1}{5}\)
3\(x\) - \(\dfrac{3}{2}\) - 5\(x\) - 3 = - \(x\) + \(\dfrac{1}{5}\)
- \(x\) + 5\(x\) - 3\(x\) = - \(\dfrac{3}{2}\) - 3 - \(\dfrac{1}{5}\)
\(x\) = - \(\dfrac{47}{10}\)
NM
18 tháng 9 2023
\(a,\dfrac{3}{7}x-\dfrac{2}{3}x=\dfrac{10}{21}\\ \Rightarrow x\left(\dfrac{3}{7}-\dfrac{2}{3}\right)=\dfrac{10}{21}\\ \Rightarrow x.-\dfrac{5}{21}=\dfrac{10}{21}\\ \Rightarrow x=-2\\ b,\dfrac{7}{35}:\left(x-\dfrac{1}{3}\right)=-\dfrac{2}{25}\\ \Rightarrow\dfrac{1}{5}:\left(x-\dfrac{1}{3}\right)=-\dfrac{2}{25}\\ \Rightarrow x-\dfrac{1}{3}=-\dfrac{5}{2}\\ \Rightarrow x=-\dfrac{13}{6}\\ c,3.\left(x-\dfrac{1}{2}\right)-5.\left(x+\dfrac{3}{5}\right)=-x+\dfrac{1}{5}\\ \Rightarrow3x-\dfrac{3}{2}-5x+5=-x+\dfrac{1}{5}\)
\(\Rightarrow x\left(3-5\right)-\dfrac{3}{2}+5=-x+\dfrac{1}{5}\\ \Rightarrow-2x-\dfrac{13}{2}=-x+\dfrac{1}{5}\\ \Rightarrow-x-\dfrac{13}{5}=\dfrac{1}{5}\\ \Rightarrow x=\dfrac{1}{5}-\dfrac{13}{5}\\ \Rightarrow x=-\dfrac{12}{5}.\)
DA
17 tháng 2 2020
d) |2x – 5| –7 = 22
| 2x -5 | = 22+7
| 2x -5 | = 29
TH1: 2x-5 = -29
2x = -29+5
2x= -24
x= -24:2
x= -12
TH2: 2x -5 =29
2x = 29+5
2x= 34
x= 34:2
x= 17
Vậy...
28 tháng 3 2020
\(a,x.\frac{-3}{7}=\frac{4}{21}\)
\(x=\frac{4}{21}:\frac{-3}{7}\)
\(x=\frac{-4}{9}\)
\(b,\frac{-4}{7}:x=\frac{2}{5}\)
\(x=\frac{-4}{7}:\frac{2}{5}\)
\(x=\frac{-10}{7}\)
\(c,x+\frac{1}{12}=\frac{-3}{8}\)
\(x=\frac{-3}{8}-\frac{1}{12}\)
\(x=\frac{-11}{24}\)
\(d,\frac{2}{15}-x=\frac{-3}{10}\)
\(x=\frac{2}{15}+\frac{3}{10}\)
\(x=\frac{13}{30}\)
28 tháng 3 2020
\(e,-x+\frac{4}{5}=\frac{1}{2}\)
\(-x=\frac{-3}{10}\)
\(x=\frac{3}{10}\)
\(f,\frac{3}{4}.\left(x+1\right)-\frac{1}{2}=\frac{3}{7}\)
\(\frac{3}{4}.\left(x+1\right)=\frac{13}{14}\)
\(x+1=\frac{26}{21}\)
\(x=\frac{5}{21}\)
\(\frac{-3}{2}-2x+\frac{3}{4}=-2\)
\(\frac{-3}{2}-2x=\frac{-11}{4}\)
\(2x=\frac{-3}{2}+\frac{11}{4}\)
\(2x=\frac{-17}{4}\)
\(x=\frac{-17}{8}\)
\(h,-x+\frac{4}{5}=\frac{1}{2}\)
\(-x=\frac{-3}{10}\)
\(x=\frac{3}{10}\)
chúc bạn học tốt !!!
SS
4
2 tháng 1 2022
\(a,x+21=6\\ \Rightarrow x=-15\\ b,x-10=-8\\ \Rightarrow x=2\\ c,\left(-8\right)x=\left(-7\right)\left(-6\right)\\ \Rightarrow\left(-8\right)x=42\\ \Rightarrow x=-4\\ d,20+8\left(x+3\right)=5^2.4\\ \Rightarrow20+8\left(x+3\right)=25.4\\ \Rightarrow20+8\left(x+3\right)=100\\ \Rightarrow8\left(x+3\right)=80\\ \Rightarrow x+3=10\\ \Rightarrow x=7\)
2 tháng 1 2022
\(a.x+21=6\\ x=6-21\\ x=-15\\ b.x-10=-8\\ x=-8+10\\ x=2\\ c.-8x=-7.\left(-6\right)-2\\ -8x=42-2\\ -8x=40\\ x=40:\left(-8\right)\\ x=-5\)
\(d.20+8\left(x+3\right)=5^2.4\\ 20+8x+24=25.4\\ 44+8x=100\\ 8x=100-44\\ 8x=56\\ x=56:8\\ x=7\)
a ) 3 10 . b ) 49 5 . c ) − 3. d ) − 15 6