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a; \(\dfrac{-x}{4}\) = \(\dfrac{-2}{x}\)
-\(x.x\) = -2.4
-\(x^2\) = -8
\(x^2\) = 8
\(\left[{}\begin{matrix}x=-\sqrt{8}\\x=\sqrt{8}\end{matrix}\right.\)
Vậy \(x\in\) {-\(\sqrt{8}\); \(\sqrt{8}\)}
Ta có :\(\frac{40+x}{77-x}=\frac{6}{7}\)
\(\Rightarrow7\left(40+x\right)=\left(77-x\right).6\)
\(\Leftrightarrow280+7x=462-6x\)
\(\Rightarrow7x+6x=462-280\)
\(\Rightarrow13x=182\)
\(\Rightarrow x=14\)
Ta có : \(\frac{10+x}{17+x}=\frac{3}{4}\)
\(\Rightarrow4\left(10+x\right)=3\left(17+x\right)\)
\(\Leftrightarrow40+4x=51+3x\)
\(\Rightarrow4x-3x=51-40\)
\(\Rightarrow x=11\)
1)
a)
\(\frac{-5}{6}.\frac{120}{25}< x< \frac{-7}{15}.\frac{9}{14}\)
\(\frac{-1}{1}.\frac{20}{5}< x< \frac{-1}{5}.\frac{3}{2}\)
\(\frac{-20}{5}< x< \frac{-3}{10}\)
\(\frac{-40}{10}< x< \frac{-3}{10}\)
\(\Rightarrow Z\in\left\{-4;-5;-6;-7;-8;-9;-10;...;-39\right\}\)
Có \(\frac{\frac{2}{7}+\frac{2}{5}+\frac{2}{17}-\frac{2}{239}}{\frac{3}{239}-\frac{3}{7}-\frac{3}{5}-\frac{3}{17}}\) : \(\frac{x}{3}\) = 2
\(\frac{2.\left(\frac{1}{7}+\frac{1}{5}+\frac{1}{17}-\frac{1}{239}\right)}{-3.\left(\frac{-1}{239}+\frac{1}{7}+\frac{1}{5}+\frac{1}{17}\right)}\) : \(\frac{x}{3}\) = 2
\(\frac{-2}{3}\) : \(\frac{x}{3}\) = 2
\(\frac{-2}{3}\) . \(\frac{3}{x}\) = 2
\(\frac{-2}{x}\) = 2
\(\Rightarrow\) x = -1
Vậy x = -1
Chúc bạn học tốt !!! ^^ #Mango
a) (x + 1/2) . (2/3 − 2x) = 0
\(\Rightarrow\left[\begin{array}{nghiempt}x+\frac{1}{2}=0\\\frac{2}{3}-2x=0\end{array}\right.\)
\(\Rightarrow\left[\begin{array}{nghiempt}x=-\frac{1}{2}\\2x=\frac{2}{3}\end{array}\right.\)
\(\Rightarrow\left[\begin{array}{nghiempt}x=-\frac{1}{2}\\x=\frac{1}{3}\end{array}\right.\)
b) \(\left(x.6\frac{2}{7}+\frac{3}{7}\right).2\frac{1}{5}-\frac{3}{7}=-2\)
\(\Rightarrow\left(x.\frac{44}{7}+\frac{3}{7}\right).\frac{11}{5}=-2+\frac{3}{7}\)
\(\Rightarrow\left(x.\frac{44}{7}+\frac{3}{7}\right).\frac{11}{5}=-\frac{11}{7}\)
\(\Rightarrow x.\frac{44}{7}+\frac{3}{7}=-\frac{11}{7}:\frac{11}{5}=-\frac{11}{7}.\frac{5}{11}\)
\(\Rightarrow x.\frac{44}{7}+\frac{3}{7}=-\frac{5}{7}\)
\(\Rightarrow x.\frac{44}{7}=-\frac{5}{7}-\frac{3}{7}\)
\(\Rightarrow x.\frac{44}{7}=-\frac{8}{7}\)
\(\Rightarrow x=-\frac{8}{7}:\frac{44}{7}=-\frac{8}{7}.\frac{7}{44}\)
\(\Rightarrow x=-\frac{2}{11}\)
c) \(x.3\frac{1}{4}+\left(-\frac{7}{6}\right).x-1\frac{2}{3}=\frac{5}{12}\)
\(\Rightarrow x\left(3\frac{1}{4}-\frac{7}{6}\right)=\frac{5}{12}+\frac{5}{3}\)
\(\Rightarrow x\left(\frac{13}{4}-\frac{7}{6}\right)=\frac{25}{12}\)
\(\Rightarrow x.\frac{25}{12}=\frac{25}{12}\)
\(\Rightarrow x=\frac{25}{12}:\frac{25}{12}\)
\(\Rightarrow x=1\)
d) \(5\frac{8}{17}:x+\left(-\frac{4}{17}\right):x+3\frac{1}{7}:17\frac{1}{3}=\frac{4}{11}\)
\(\Rightarrow\left(5\frac{8}{17}-\frac{4}{17}\right):x+\frac{22}{7}:\frac{52}{3}=\frac{4}{11}\)
\(\Rightarrow5\frac{4}{17}:x+\frac{33}{182}=\frac{4}{11}\)
\(\Rightarrow\frac{89}{17}:x=\frac{4}{11}-\frac{33}{182}\)
\(\Rightarrow\frac{89}{17}:x=\frac{365}{2002}\)
\(\Rightarrow x=\frac{89}{17}:\frac{365}{2002}\)
\(\Rightarrow x\approx28,7\) (số hơi lẻ)
e) \(\frac{17}{2}-\left|2x-\frac{3}{4}\right|=-\frac{7}{4}\)
\(\Rightarrow\left|2x-\frac{3}{4}\right|=\frac{17}{2}+\frac{7}{4}\)
\(\Rightarrow\left|2x-\frac{3}{4}\right|=\frac{41}{4}\)
\(\Rightarrow\left[\begin{array}{nghiempt}2x-\frac{3}{4}=\frac{41}{4}\\2x-\frac{3}{4}=-\frac{41}{4}\end{array}\right.\)
\(\Rightarrow\left[\begin{array}{nghiempt}2x=11\\2x=-\frac{19}{2}\end{array}\right.\)
\(\Rightarrow\left[\begin{array}{nghiempt}x=\frac{11}{2}\\x=-\frac{19}{4}\end{array}\right.\)
Bài 2 :x+1/3=x-3/4 <=>4.(x+1)=3.(x-3) 4x+4=3x-9 4x-3x=-9-4 x=-13
Bài 1:
ta có: \(\frac{17}{x+1}.\frac{x}{6}=\frac{17x}{6x+6}\)
Để 17x/6x+6 thuộc Z
=> 17x chia hết cho 6x + 6
=> 102x chia hết cho 6x + 6
102x + 102 - 102 chia hết cho 6x + 6
17.(6x+6) - 102 chia hết cho 6x+6
mà 17.(6x+6) chia hết cho 6x + 6
=> 102 chia hết cho 6x + 6
=> ...
bn tự lm típ nha!
Bài 2:
ta có: \(\frac{x+1}{3}=\frac{x-3}{4}\)
\(\Rightarrow4x+4=3x-9\)
\(\Rightarrow4x-3x=-9-4\)
\(x=-13\)
\(\Leftrightarrow\frac{-2}{17}\le\frac{x}{17}\le\frac{2}{17}\Rightarrow x\in\left(-2;-1;0;1;2\right)\)
\(\Leftrightarrow\frac{-1}{24}\le\frac{x}{24}\le\frac{5}{24}\Rightarrow x\in\left(-1;0;1;2;3;4;5\right)\)
2 câu sau tự làm nha
\(-\frac{5}{17}+\frac{3}{17}\le\frac{x}{17}\le\frac{13}{17}+-\frac{11}{17}\)
\(\frac{-2}{17}\le\frac{x}{17}\le\frac{2}{17}\)
=> \(x\in\left\{-2;-1;0;1;2\right\}\)
b) <=> 4(10+x) = 3(17+x)
40+4x=51+3x
4x-3x=51-40
x=11
c) <=> 7.(40+x) = 6 .(17+x)
280+7x =102 + 6x
7x-6x=102-280
x=-178
a) 7/x=x/28
=)7*28=x*x
=)196=x^2
=)14^2=x^2
= )x=14
k cho mih di roi mih giai tiep cho nha