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Câu a:
2.(x + 2/5) + 1 1 /4 = 11/20
2x + 4/5 + 5/4 = 11/20
2x = 11/20 - 5/4 - 4/5
2x = 11/20 - 25/20 - 16/20
2x = -30/20
2x = -3/2
x = -3/2 : 2
x = - 3/4
Vậy x = - 3/4
Câu b:
x - 1 1/8 - 2/3x - 5/6x = 75%
(x - 2/3x - 5/6x) = 75% + 1 1/8
x (1 - 2/3 - 5/6) = 3/4 + 9/8
x (6/6 - 4/6 - 5/6) = 6/8 + 9/8
x.(-1/2) = 15/8
x = 15/8 : (-1/2)
x = 15/8 x (-2)
= -15/4
a) \(2.\left(x+\frac{2}{5}\right)+1\frac{1}{4}=\frac{11}{20}\)
\(2.\left(x+\frac{2}{5}\right)+\frac{5}{4}=\frac{11}{20}\)
\(2.\left(x+\frac{2}{5}\right)=\frac{-7}{10}\)
\(x+\frac{2}{5}=\frac{-7}{20}\)
\(x=\frac{-13}{20}\)
Vậy \(x=\frac{-13}{20}\)
b)\(x-1\frac{1}{8}-\frac{2}{3}x-\frac{5}{6}x=75\%\)
\(\left(x-\frac{2}{3}x-\frac{5}{6}x\right)-\frac{9}{8}=\frac{3}{4}\)
\(\frac{-1}{2}x-\frac{9}{8}=\frac{3}{4}\)
\(\frac{-1}{2}x=\frac{15}{8}\)
\(x=\frac{-15}{4}\)
Vậy \(x=\frac{-15}{4}\)
1.
2|x-6|+7x-2=|x-6|+7x
2|x-6| - |x-6|=7x-(7x-2)
|x-6| = 2
=>x-6 = +2
*x-6=2 *x-6 = -2
x =2+6 x = (-2)+6
x =8 x = 4
2.
|x-5|-7(x+4)=5-7x
|x-5|-7x-28 =5-7x
|x-5|-28 =5-7x+7x
|x-5|-28 = 5
|x-5| = 5+28
|x-5| = 33
=>x-5 = +33
*x-5=33 *x-5=-33
x =38 x = -28
3.
3|x+4|-2(x-1)=7-2x
3|x+4|-2x+2 =7-2x
3|x+4|-2 =7-2x+2x
3|x+4|-2 =7
3|x+4| =7+2
3|x+4| = 9
|x+4| =9:3
|x+4| = 3
=>x+4 = +3
*x+4=3 *x+4=-3
x =-1 x = -7
Bài 2a:
Tìm x
5/3x + 2/3 = 1/4
5/3x = 1/4 - 2/3
5/3x = 3/12 - 8/12
5/3x = - 5/12
x = -5/12 : 5/3
x = -5/12 x 3/5
x = - 1/4
Vậy x = -1/ 4
\(5^x-2-3^2=2^4-\left(2^8x2^4-2^{10}x2^2\right)\)
\(5^x-2-3^2=2^4-\left(2^{8+4}-2^{10+2}\right)\)
\(5^x-2-3^2=2^4-\left(2^{12}-2^{12}\right)\)
\(5^x-2-3^2=2^4-0\)
\(5^x-2-3^2=2^4\)
\(5^x-2-9=16\)
\(5^x-2=16+9\)
\(5^x-2=25\)
\(5^x=25+2\)
\(5^x=27\)
Bởi vì 27 không phân tích được 1 số có số mũ là 2
\(\Rightarrow\) Không tồn tại x
\(5^{x-2}-9=16-\left(256.16-1024.4\right)\)
\(\Rightarrow5^{x-2}-9=16-\left(4096-4096\right)\)
\(\Rightarrow5^{x-2}-9=16-0\)
\(\Rightarrow5^{x-2}-9=16\)
\(\Rightarrow5^{x-2}=25\)
\(\Rightarrow x-2=25:5\)
\(\Rightarrow x-2=3\)
\(\Rightarrow x=5\)
\(5^{x-2}-3^2=2^4-\left(2^8\cdot2^4-2^{10}\cdot2^2\right)\)
\(\Rightarrow5^{x-2}-3^2=2^4-\left(2^{12}-2^{12}\right)\)
\(\Rightarrow5^{x-2}-9=16-0\)
\(\Rightarrow5^{x-2}=16+9\)
\(\Rightarrow5^{x-2}=25\)
\(\Rightarrow5^{x-2}=5^2\)
\(\Rightarrow x-2=2\)
\(\Rightarrow x=2+2\)
\(\Rightarrow x=4\)
Vậy: x=4