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Có:
\(x\dfrac{x}{15}=\dfrac{112}{5}\)
Hay \(\dfrac{x.15+x}{15}=\dfrac{112}{5}\)
\(\Rightarrow x.15+x=\dfrac{112.15}{5}=336\)
\(x.\left(15+1\right)=336\)
\(x.16=336\)
\(\Rightarrow x=\dfrac{336}{16}=21\)
Chúc bạn học tốt!
a) \(\dfrac{-5}{6}.\dfrac{120}{25}< x< \dfrac{-7}{15}.\dfrac{9}{14}\)
\(\Rightarrow-4< x< \dfrac{-3}{10}\)
\(\Rightarrow\dfrac{-40}{10}< x< \dfrac{-3}{10}\)
\(\Rightarrow x\in\left\{\dfrac{-39}{10};\dfrac{-38}{10};\dfrac{-37}{10};...;\dfrac{-5}{10};\dfrac{-4}{10}\right\}\)
b) \(\left(\dfrac{-5}{3}\right)^2< x< \dfrac{-24}{35}.\dfrac{-5}{6}\)
\(\Rightarrow\dfrac{25}{9}< x< \dfrac{4}{7}\)
\(\Rightarrow\dfrac{175}{63}< x< \dfrac{36}{63}\)
\(\Rightarrow x=\varnothing\)
c) \(\dfrac{1}{18}< \dfrac{x}{12}< \dfrac{y}{9}< \dfrac{1}{4}\)
\(\Leftrightarrow\dfrac{2}{36}< \dfrac{3x}{36}< \dfrac{4y}{36}< \dfrac{9}{36}\)
\(\Rightarrow x\in\left\{1;2\right\}\)
+) Với \(x=1\)
\(\Rightarrow y\in\left\{1;2\right\}\)
+) Với \(x=2\)
\(\Rightarrow y=2\)
Vậy \(x=1\) thì \(y\in\left\{1;2\right\}\); \(x=2\) thì \(y=8\).
b) \(\dfrac{1}{3}+\dfrac{1}{6}+\dfrac{1}{10}+...+\dfrac{2}{x\left(x+1\right)}=\dfrac{499}{1000}\)
\(\dfrac{2}{6}+\dfrac{2}{12}+\dfrac{2}{20}+...+\dfrac{2}{x\left(x+1\right)}=\dfrac{499}{1000}\)
\(\dfrac{2}{2.3}+\dfrac{2}{3.4}+\dfrac{2}{4.5}+...+\dfrac{2}{x\left(x+1\right)}=\dfrac{499}{1000}\)
\(\frac{x}{3}=\frac{2}{3}+\frac{-1}{7}\)
=>\(\frac{x}{3}=\frac{11}{21}\)
=>x=\(\frac{11}{21}\cdot3=\frac{33}{21}\)
=>x=\(\frac{11}{7}\)
=>x/3 =11/21
Theo tính chất p số = nhau
=>x.21=3.11
x =33:21=11/7
\(6\dfrac{2}{9}.x+3\dfrac{10}{27}=22\dfrac{1}{7}\)
\(\dfrac{56}{9}.x+\dfrac{91}{27}=\dfrac{155}{7}\)
\(\left(\dfrac{56}{9}.x\right)\) \(=\dfrac{155}{7}-\dfrac{91}{27}\)
\(\left(\dfrac{56}{9}.x\right)\) \(=\dfrac{4185}{189}-\dfrac{637}{189}\)
\(\left(\dfrac{56}{9}.x\right)\) \(=\dfrac{3548}{189}\)
\(x\) \(=\dfrac{3548}{189}:\dfrac{56}{9}\)
\(x\) \(=\dfrac{3548}{189}.\dfrac{9}{56}\)
\(x\) \(=\dfrac{887}{294}\)
Vậy \(x\\\) \(=\dfrac{887}{294}\)
Chúc bạn học tốt
\(\dfrac{-1}{4}< \dfrac{x}{24}< \dfrac{-1}{6}\\ \dfrac{-6}{24}< \dfrac{x}{24}< \dfrac{-4}{24}\\ \Rightarrow x=-5\)
a)=>1 - (5+x-7)=0
=>5+x-7 =1
=>5+x =8
=>x=3
Câu b) thiếu giá trị nha bạn
Mk học Trường THCS Nhơn Thọ ko phải
Trường THCS Lộc Ngãi nhưng mk cũng sẽ giúp bạn cho.
a) 1-( 5\(\dfrac{3}{8}\)+x-7\(\dfrac{5}{24}\)) : 16\(\dfrac{2}{3}\)=0
1-(\(\dfrac{43}{8}\)+x-\(\dfrac{173}{24}\)) : \(\dfrac{50}{3}\)=0
Xin lỗi nha câu a mk làm tới đây mk bận r không thể làm tiếp cho bạn nữa
Xin lỗi nha
\(\dfrac{6}{x}=\dfrac{24}{x-27}\)
Theo định nghĩa phân số bằng nhau, ta có:
\(6\cdot\left(x-27\right)=24x\\ 6x-162=24x\\ -162=24x-6x\\ -162=18x\\ x=\left(-162\right):18\\ x=-9\)
Theo bài ra ta có:
6.(x-27)=x.24
6x-162=x.24
-162=24x-6x
-162=18x
x =(-162):18
x = -9
tick mk nha 
\(\dfrac{6}{-x}=\dfrac{x}{-24}\)
\(-144=-x^2\)
\(-144=12\cdot\left(-12\right)\)
\(\Rightarrow x=\left[{}\begin{matrix}12\\-12\end{matrix}\right.\)
6/-6= 24/-24