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1) 2⁴.x - 3.5x = 5² - 2⁴
16x - 15x = 25 - 16
x = 9
2) 3².x + 2²x = 26.2² - 13
9x + 4x = 26.4 - 13
13x = 104 - 13
13x = 91
x = 91 : 13
x = 7
5) 6²x - 5²x = 11.2 - 11
36x - 25x = 22 - 11
11x = 11
x = 11 : 11
x = 1
3) 5²x - 2⁴x = 3⁴ - 16.3²
25x - 16x = 81 - 16.9
9x = -63
x = -63 : 9
x = -7
6) 7²x - 6²x = 13.2³ - 26
49x - 36x = 13.8 - 26
13x = 104 - 26
13x = 78
x = 78 : 13
x = 6
4) 7²x - 14x = 7².10 - 70
49x - 14x = 49.10 - 70
35x = 490 - 70
35x = 420
x = 420 : 35
x = 12
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1) Ta có: \(\left(-\dfrac{2}{3}\right)^2\cdot\dfrac{-9}{8}-25\%\cdot\dfrac{-16}{5}\)
\(=\dfrac{4}{9}\cdot\dfrac{-9}{8}-\dfrac{1}{4}\cdot\dfrac{-16}{5}\)
\(=\dfrac{-1}{2}+\dfrac{4}{5}\)
\(=\dfrac{-5}{10}+\dfrac{8}{10}=\dfrac{3}{10}\)
2) Ta có: \(-1\dfrac{2}{5}\cdot75\%+\dfrac{-7}{5}\cdot25\%\)
\(=\dfrac{-7}{5}\cdot\dfrac{3}{4}+\dfrac{-7}{5}\cdot\dfrac{1}{4}\)
\(=\dfrac{-7}{5}\left(\dfrac{3}{4}+\dfrac{1}{4}\right)=-\dfrac{7}{5}\)
3) Ta có: \(-2\dfrac{3}{7}\cdot\left(-125\%\right)+\dfrac{-17}{7}\cdot25\%\)
\(=\dfrac{-17}{7}\cdot\dfrac{-5}{4}+\dfrac{-17}{7}\cdot\dfrac{1}{4}\)
\(=\dfrac{-17}{7}\cdot\left(\dfrac{-5}{4}+\dfrac{1}{4}\right)\)
\(=\dfrac{17}{7}\)
4) Ta có: \(\left(-2\right)^3\cdot\left(\dfrac{3}{4}\cdot0.25\right):\left(2\dfrac{1}{4}-1\dfrac{1}{6}\right)\)
\(=\left(-8\right)\cdot\left(\dfrac{3}{4}\cdot\dfrac{1}{4}\right):\left(\dfrac{9}{4}-\dfrac{7}{6}\right)\)
\(=\left(-8\right)\cdot\dfrac{3}{16}:\dfrac{54-28}{24}\)
\(=\dfrac{-3}{2}\cdot\dfrac{24}{26}\)
\(=\dfrac{-72}{52}=\dfrac{-18}{13}\)
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Ta có: 72x-62x = 13.23-26 => x(72-62) = 13.8-26 => 13x = 78 => x = 78:13 => x = 6 Vậy, x = 6.
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(x-5)x \(\frac{30}{100}\)=\(\frac{20}{100}\)X+5
30x-150=20x500
10x=650
x=65
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\(\left(x+1\right)^3=2^3.3+3\)
\(\Rightarrow\left(x+1\right)^3=24+3=27=3^3\)
\(\Rightarrow x+1=3\Rightarrow x=2\)
\(5+2.3^x+2=23\)
\(\Rightarrow7+2.3^x=23\)
\(\Rightarrow2.3^x=23-7=16\)
\(\Rightarrow3^x=8.\)
Mà số 3 lũy thừa mấy cũng không thể bằng 8 => x không thỏa mãn.
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Lời giải:
$(x-12)+14=2^3.3=8.3=24$
$x-12=24-14=10$
$x=12+10=22$
Đáp án C
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$2021-5(x+4)=1^{2022}=1$
$5(x+4)=2021-1=2020$
$x+4=404$
$x=400$
Đáp án B.
giúp mình với mình đang cần gấp
Gía trị biểu thức trên là12