Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
Giải:
\(7,5x:\left(9-6\dfrac{13}{21}\right)=2\dfrac{13}{25}\)
\(\Leftrightarrow7,5x:\left(9-\dfrac{139}{21}\right)=\dfrac{43}{25}\)
\(\Leftrightarrow7,5x:\dfrac{50}{21}=\dfrac{43}{25}\)
\(\Leftrightarrow7,5x=\dfrac{43}{25}.\dfrac{50}{21}\)
\(\Leftrightarrow7,5x=\dfrac{86}{21}\)
\(\Leftrightarrow x=\dfrac{86}{21}:7,5\)
\(\Leftrightarrow x=\dfrac{172}{315}\)
Vậy ...
a: Đề sai rồi bạn
b: \(\dfrac{\left(1.16-x\right)\cdot5.25}{\left(10+\dfrac{5}{9}-7-\dfrac{1}{4}\right)\cdot\dfrac{36}{17}}=\dfrac{3}{4}\)
\(\Leftrightarrow21\left(1.16-x\right)=3\cdot\dfrac{36}{17}\cdot\left(3+\dfrac{5}{9}-\dfrac{1}{4}\right)\)
\(\Leftrightarrow21\left(1.16-x\right)=\dfrac{108}{17}\cdot\dfrac{108+20-9}{36}\)
\(\Leftrightarrow21\cdot\left(1.16-x\right)=21\)
=>1,16-x=1
hay x=0,16
1.a) Dễ nhận thấy đề toán chỉ giải được khi đề là tìm x,y. Còn nếu là tìm x ta nhận thấy ngay vô nghiệm. Do đó: Sửa đề: \(\left|x-3\right|+\left|2-y\right|=0\)
\(\Leftrightarrow\left|x-3\right|=\left|2-y\right|=0\)
\(\left|x-3\right|=0\Rightarrow\left\{{}\begin{matrix}x-3=0\\-\left(x-3\right)=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=3\\x=-3\end{matrix}\right.\) (1)
\(\left|2-y\right|=0\Rightarrow\left\{{}\begin{matrix}2-y=0\\-\left(2-y\right)=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}y=2\\y=-2\end{matrix}\right.\) (2)
Từ (1) và (2) có: \(\left[{}\begin{matrix}\left\{{}\begin{matrix}x_1=3\\x_2=-3\end{matrix}\right.\\\left\{{}\begin{matrix}y_1=2\\y_2=-2\end{matrix}\right.\end{matrix}\right.\)
Câu 1:
a,\(x=\dfrac{1}{4}+\dfrac{2}{13}\)
\(x=\dfrac{13}{52}+\dfrac{8}{52}=\dfrac{21}{52}\)
Câu 2:
a,\(\dfrac{-2}{5}+\dfrac{3}{-4}+\dfrac{6}{7}+\dfrac{3}{4}+\dfrac{2}{5}\)
\(=\left(\dfrac{-2}{5}+\dfrac{2}{5}\right)+\left(\dfrac{3}{-4}+\dfrac{3}{4}\right)+\dfrac{6}{7}\)
=\(0+0+\dfrac{6}{7}=\dfrac{6}{7}\)
b,\(\dfrac{7}{15}+\dfrac{4}{-9}+\dfrac{-2}{11}+\dfrac{8}{15}+\dfrac{-5}{9}\)
=\(\left(\dfrac{7}{15}+\dfrac{8}{15}\right)+\left(\dfrac{4}{-9}+\dfrac{-5}{9}\right)+\dfrac{-2}{11}\)
=\(\dfrac{15}{15}+\dfrac{-9}{9}+\dfrac{-2}{11}=1+\left(-1\right)+\dfrac{-2}{11}\)
=\(0+\dfrac{-2}{11}=\dfrac{-2}{11}\)
c, \(\dfrac{-5}{7}+\dfrac{5}{13}+\dfrac{-20}{41}+\dfrac{8}{13}+\dfrac{-21}{41}\)
=\(\left(\dfrac{5}{13}+\dfrac{8}{13}\right)+\left(\dfrac{-20}{41}+\dfrac{-21}{41}\right)+\dfrac{-5}{7}\)
=\(\dfrac{13}{13}+\dfrac{-41}{41}+\dfrac{-5}{7}=1+\left(-1\right)+\dfrac{-5}{7}\)
=\(0+\dfrac{-5}{7}=\dfrac{-5}{7}\)
a, \(\dfrac{x}{13}=\dfrac{35}{91}\Leftrightarrow\dfrac{x}{13}=\dfrac{5}{13}\Leftrightarrow x=5\)
b, \(\dfrac{9+x}{13-x}=\dfrac{5}{6}\Leftrightarrow\dfrac{9+x}{13-x}=\dfrac{10}{12}\Leftrightarrow x=1\)
@đỗ hương giang
a.
\(\dfrac{x}{13}=\dfrac{35}{91}\)
\(\Rightarrow x=\dfrac{35.13}{91}=5\)
Vậy x = 5
b.
\(\dfrac{9+x}{13-x}=\dfrac{5}{6}\)
\(\Rightarrow\dfrac{9+x}{13-x}=\dfrac{10}{12}\)
\(\Rightarrow\dfrac{x=10-9}{13-12=x}\Rightarrow x=\dfrac{1}{1}=1\)
Vậy x =1
c.
x + x : 5 . 7,5 + x : 2.9 = 315
\(\Rightarrow x+\dfrac{x}{5}7,5+\dfrac{x}{2}9=7x\)
\(\Rightarrow7x=3^3.5\)
\(\Rightarrow7x=135\)
\(\Rightarrow x=\dfrac{135}{7}\)
Vậy x = \(\dfrac{135}{7}\)
Chúc bạn học tốt!!!
a, Đề sai hả bạn ??
b, \(\dfrac{\left(1,16-x\right).5,25}{\left(10\dfrac{5}{9}-7\dfrac{1}{4}\right).2\dfrac{2}{17}}=75\%\)
\(\dfrac{\left(1,16-x\right).5,25}{\left(\dfrac{95}{9}-\dfrac{29}{4}\right).\dfrac{36}{17}}=\dfrac{75}{100}\)
\(\dfrac{\left(1,16-x\right).5,25}{\left(\dfrac{380}{36}-\dfrac{261}{36}\right).\dfrac{36}{17}}=\dfrac{3}{4}\)
\(\dfrac{\left(1,16-x\right).5,25}{\dfrac{119}{36}.\dfrac{36}{17}}=\dfrac{3}{4}\)
\(\dfrac{\left(1,16-x\right).5,25}{7}=\dfrac{3}{4}\)
=> \(\left[\left(1,16-x\right).5,25\right].4=3.7\)
\(\left[\left(1,16-x\right).5,25\right].4=21\)
( 1,16 - x ) . 5,25 = 21/4
1,16 - x = 21/4 : 5,25
1,16 - x = 1
x = 1,16 - 1
x = 0,16
Vậy x = 0,16
c, \(\left(\dfrac{1}{1.3}+\dfrac{1}{3.5}+...+\dfrac{1}{19.21}\right).420-\left[0,4.\left(7,5-2,5x\right)\right]:0,25=212\)
\(\dfrac{1}{2}.\left(\dfrac{2}{1.3}+\dfrac{2}{3.5}+...+\dfrac{2}{19.21}\right).420-\left[0,4.\left(7,5-2,5x\right)\right]:0,25=212\)
\(\dfrac{1}{2}.\left(\dfrac{1}{1}-\dfrac{1}{21}\right).420-\left[0,4.\left(7,5-2,5x\right)\right]:0,25=212\)
\(\dfrac{1}{2}.\dfrac{20}{21}.420-\left[0,4.\left(7,5-2,5x\right)\right]:0,25=212\)
\(200-\left[0,4.\left(7,5-2,5x\right)\right]:0,25=212\)
\(0,4.\left(7,5-2,5x\right):0,25=200-212\)
\(0,4.\left(7,5-2,5x\right):0,25=-12\)
0,4 . ( 7,5 - 2,5x ) = -12 . 0,25
0,4 . ( 7,5 - 2,5x ) = -3
7,5 - 2,5x = -3 :0,4
7,5 - 2,5x = -7,5
2,5x = 7,5-(-7,5)
2,5x = 15
x = 6
Vậy x = 6
Vậy x = 51
câu a chắc mk nhìn ko rõ vì mk cận mà ko đeo kính, ghi sai đề
Bài 1: Tính ( hợp lý nếu có thể )
\(A=\dfrac{-3}{8}+\dfrac{12}{25}+\dfrac{5}{-8}+\dfrac{2}{-5}+\dfrac{13}{25}\)
\(=\left(\dfrac{-3}{8}+\dfrac{5}{-8}\right)+\left(\dfrac{12}{25}+\dfrac{13}{25}\right)+\dfrac{2}{-5}\)
\(=-1+1+\dfrac{2}{-5}\)
\(=0+\dfrac{2}{-5}\)
\(=\dfrac{2}{-5}\)
\(B=\dfrac{-3}{15}+\left(\dfrac{2}{3}+\dfrac{3}{15}\right)\)
\(=\left(\dfrac{-3}{15}+\dfrac{3}{15}\right)+\dfrac{2}{3}\)
\(=0+\dfrac{2}{3}\)
\(=\dfrac{2}{3}\)
\(C=\dfrac{-5}{21}+\left(\dfrac{-16}{21}+1\right)\)
\(=\left(\dfrac{-5}{21}+\dfrac{-16}{21}\right)+1\)
\(=-1+1\)
\(=0\)
\(D=\left(\dfrac{-1}{6}+\dfrac{5}{-12}\right)+\dfrac{7}{12}\)
\(=\left(\dfrac{5}{-12}+\dfrac{7}{12}\right)+\dfrac{-1}{6}\)
\(=\dfrac{1}{6}+\dfrac{-1}{6}\)
\(=0\)
Bài 2: Tìm x,biết:
a) \(x+\dfrac{2}{3}=\dfrac{4}{5}\)
\(x=\dfrac{4}{5}-\dfrac{2}{3}\)
\(x=\dfrac{2}{15}\)
Vậy \(x=\dfrac{2}{15}\)
b) \(x-\dfrac{2}{3}=\dfrac{7}{21}\)
\(\Rightarrow x-\dfrac{2}{3}=\dfrac{1}{3}\)
\(x=\dfrac{1}{3}+\dfrac{2}{3}\)
\(x=\dfrac{3}{3}=1\)
Vậy \(x=1\)
c) sai đề hay sao ấy bạn.bỏ dấu - ở x thì đúng đề.mk giải luôn nha!
\(x-\dfrac{3}{4}=\dfrac{-8}{11}\)
\(x=\dfrac{-8}{11}+\dfrac{3}{4}\)
\(x=\dfrac{1}{44}\)
Vậy \(x=\dfrac{1}{44}\)
d) \(\dfrac{11}{12}-\left(\dfrac{2}{5}+x\right)=\dfrac{2}{3}\)
\(\dfrac{2}{5}+x=\dfrac{11}{12}-\dfrac{2}{3}\)
\(\dfrac{2}{5}+x=\dfrac{1}{4}\)
\(x=\dfrac{1}{4}-\dfrac{2}{5}\)
\(x=-\dfrac{3}{20}\)
Vậy \(x=-\dfrac{3}{20}\)
Các bạn không cần trả lời câu hỏi trên của mik vì mik đã hiểu rồi nha . Cho nên đừng trả lời ! OK
7 . 5x : (9 - 6\(\dfrac{13}{21}\)) = 2\(\dfrac{13}{25}\)
7 . 5x : 2\(\dfrac{8}{21}\) = 2\(\dfrac{13}{25}\)
7 . 5x = 2\(\dfrac{13}{25}\) . 2\(\dfrac{8}{21}\)
7 . 5x = 6
5x = 6 : 7
5x = 6 . \(\dfrac{1}{7}\)
5x = \(\dfrac{6}{7}\)