\(x+12=31\cdot2\)
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Những câu hỏi liên quan
\(2^{x+1}\cdot2^y=12^x\)
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\(2^y=12^x:2^{x+1}\)
=> \(2^y=12^x:2^x.2=6^x.2\)
=> \(2^y:2=6^x=2^{y-1}\)
Em xem lại đề nhé
tìm \(x\inℕ,\)biết:
\(2\cdot2^2+3\cdot2^3+4\cdot2^4+....+x\cdot2^x=2^{x+1}\)
Tìm x\(\in\)Z biết:
\(2\cdot2^2\cdot2^3\cdot2^4\cdot...\cdot2^x=1024\)
\(2^1.2^2.2^3.....2^x=1024\Rightarrow2^{1+2+3+...+x}=2^{10}\)
\(\Rightarrow1+2+3+...+x=1024\Rightarrow x=4\)
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1 ) Tìm x biết
a) \(x^{10}\cdot\left(x^2\right)^{10}\cdot\left(x^3\right)^{10}\cdot...\cdot\left(x^{10}\right)^{10}\)
b)\(\frac{1}{2}\cdot2^x+4\cdot2^x=9\cdot2^5\)
c)\(3\cdot2^{x+2}=5\cdot2^3\)
a)\(\frac{\left(3\cdot4\cdot2^{16}\right)^2}{11\cdot2^{13}\cdot4^{11}-16^9}\)
b\(\left(1\cdot2\cdot3....\cdot9-1\cdot2\cdot3.....\cdot8-1\cdot2\cdot3....7\cdot8^2\right)\)
c)1152-(374+1152)+(-65+374)
d)(10^2+11^2+12^2):(13^2+14^2)
tính nhanh
25/37 x 18/29 + 18/29 x 12/37
31/85 x 11/19 + 31/85 x 12/19 - 42/19 x 31/85
c , 16/53 : 17/9 - 16/53 : 17/8
1/5 x 12/31 x 4/3 + 19/31 x 4/15
a) \(\dfrac{25}{37}\times\dfrac{18}{29}+\dfrac{18}{29}\times\dfrac{12}{37}\)
\(=\dfrac{18}{29}\times\left(\dfrac{25}{37}+\dfrac{12}{37}\right)\)
\(=\dfrac{18}{29}\times\dfrac{37}{37}\)
\(=\dfrac{18}{29}\times1\)
\(=\dfrac{18}{29}\)
b) \(\dfrac{31}{85}\times\dfrac{11}{19}+\dfrac{31}{85}\times\dfrac{12}{19}-\dfrac{42}{19}\times\dfrac{31}{85}\)
\(=\dfrac{31}{85}\times\left(\dfrac{11}{19}+\dfrac{12}{19}-\dfrac{42}{19}\right)\)
\(=\dfrac{31}{85}\times\dfrac{-19}{19}\)
\(=\dfrac{31}{85}\times-1\)
\(=-\dfrac{31}{85}\)
c) \(\dfrac{16}{53}:\dfrac{17}{9}-\dfrac{16}{53}:\dfrac{17}{8}\)
\(=\dfrac{16}{53}:\left(\dfrac{9}{17}-\dfrac{8}{17}\right)\)
\(=\dfrac{16}{53}:\dfrac{1}{17}\)
\(=\dfrac{16}{901}\)
c) \(\dfrac{1}{5}\times\dfrac{12}{31}\times\dfrac{4}{3}+\dfrac{19}{31}\times\dfrac{4}{15}\)
\(=\dfrac{4}{15}\times\dfrac{12}{31}+\dfrac{19}{31}\times\dfrac{4}{15}\)
\(=\dfrac{4}{15}\times\left(\dfrac{12}{31}+\dfrac{19}{31}\right)\)
\(=\dfrac{4}{15}\times\dfrac{31}{31}\)
\(=\dfrac{4}{15}\times1\)
\(=\dfrac{4}{15}\)
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a: =18/29*(25/37+12/37)
=18/29
b: =31/85(11/19+12/19-42/19)
=-31/85
c; =16/53(9/17+8/17)=16/53
d: =4/15(12/31+19/31)=4/15
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\(^{2^{x+1}\cdot2^1+4\cdot2^x}\)
tìm x biết
1)\(-\frac{2}{3}\cdot\left(x-\frac{1}{4}\right)=\frac{1}{3}\cdot\left(2x-1\right)\)
2)\(\frac{1}{5}\cdot2^x+\frac{1}{5}\cdot2^{x+1}=\frac{1}{5}\cdot2^7+\frac{1}{3}\cdot2^8\)
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TV
29 tháng 3 2023 lúc 21:09
Cho phương trình : \(x^2-2\left(m+1\right)x-12=0\)
Tìm m để phương trình có nghiệm x1, x2 thỏa mãn : \(x_1^2-x_2^2-7\cdot2\cdot\left(m+1\right)=0\)
\(ac=-12< 0\) nên pt luôn có 2 nghiệm pb trái dấu
Theo hệ thức Viet: \(\left\{{}\begin{matrix}x_1+x_2=2\left(m+1\right)\\x_1x_2=-12\end{matrix}\right.\)
\(x_1^2-x_2^2-14\left(m+1\right)=0\)
\(\Leftrightarrow\left(x_1-x_2\right)\left(x_1+x_2\right)-14\left(m+1\right)=0\)
\(\Leftrightarrow\left(x_1-x_2\right).2\left(m+1\right)-14\left(m+1\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}m=-1\\x_1-x_2=7\left(1\right)\end{matrix}\right.\)
Xét (1), kết hợp với Viet ta được: \(\left\{{}\begin{matrix}x_1+x_2=2\left(m+1\right)\\x_1-x_2=7\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}x_1=\dfrac{2m+9}{2}\\x_2=\dfrac{2m-5}{2}\end{matrix}\right.\)
Thế vào \(x_1x_2=-12\Leftrightarrow\left(\dfrac{2m+9}{2}\right)\left(\dfrac{2m-5}{2}\right)=-12\)
\(\Leftrightarrow4m^2+8m+3=0\Rightarrow\left[{}\begin{matrix}m=-\dfrac{3}{2}\\m=-\dfrac{1}{2}\end{matrix}\right.\)
Vậy \(m=\left\{-1;-\dfrac{3}{2};-\dfrac{1}{2}\right\}\)
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