Tìm x, biết: \(\frac{1}{2}\cdot2^x+4\cdot2^x-288=0\)
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\(\frac{1}{3}x+\frac{2}{5}\left(x-1\right)=0\)
\(\Leftrightarrow\frac{1}{3}x+\frac{2}{5}x-\frac{2}{5}=0\)
\(\Leftrightarrow\frac{1}{3}x+\frac{2}{5}x=0+\frac{2}{5}\)
\(\Leftrightarrow x\left(\frac{1}{3}+\frac{2}{5}\right)=\frac{2}{5}\)
\(\Leftrightarrow x\left(\frac{5}{15}+\frac{6}{15}\right)=\frac{2}{5}\)
\(\Leftrightarrow\frac{11}{15}x=\frac{2}{5}\)
\(\Leftrightarrow x=\frac{2}{5}\div\frac{11}{15}\)
\(\Leftrightarrow x=\frac{6}{11}\)
\(\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+...+\frac{2}{x\left(x+1\right)}=\frac{49}{50}\)
\(\Leftrightarrow\frac{2}{6}+\frac{2}{12}+\frac{2}{20}+...+\frac{2}{x\left(x+1\right)}=\frac{49}{50}\)
\(\Leftrightarrow2\left(\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{x\left(x+1\right)}\right)=\frac{49}{50}\)
\(\Leftrightarrow2\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{x}-\frac{1}{x+1}\right)=\frac{49}{50}\)
\(\Leftrightarrow2\left(\frac{1}{2}-\frac{1}{x+1}\right)=\frac{49}{50}\)
\(\Leftrightarrow\frac{1}{2}-\frac{1}{x+1}=\frac{49}{50}\div2\)
\(\Leftrightarrow\frac{1}{2}-\frac{1}{x+1}=\frac{49}{50}\times\frac{1}{2}\)
\(\Leftrightarrow\frac{1}{2}-\frac{1}{x+1}=\frac{49}{100}\)
\(\Leftrightarrow\frac{1}{x+1}=\frac{1}{2}-\frac{49}{100}\)
\(\Leftrightarrow\frac{1}{x+1}=\frac{50}{100}-\frac{49}{100}\)
\(\Leftrightarrow\frac{1}{x+1}=\frac{1}{100}\)
\(\Leftrightarrow x+1=100\)
\(\Leftrightarrow x=100-1\)
\(\Leftrightarrow x=99\)
a, <=> (x-2)2=25
<=>x-2=5 hoặc x-2=-5
<=>x=7 hoặc x=-3
c,<=>(x2)2-16=0
<=>(x2)2=16
<=>x2=4
<=>x=2 hoặc x=-2
\(2^1.2^2.2^3.....2^x=1024\Rightarrow2^{1+2+3+...+x}=2^{10}\)
\(\Rightarrow1+2+3+...+x=1024\Rightarrow x=4\)
\(\left(\frac{1}{3}+\frac{1}{6}\right).2^{x+4}-2^x=2^{13}-2^{10}\)
\(\frac{1}{2}.2^x.2^4-2^x=8192-1024\)
\(2^x.8-2^x=7168\)
\(2^x\left(8-1\right)=7168\)
\(2^x.7=7168\)
\(2^x=7168\div7\)
\(2^x=1024\)
\(2^x=2^{10}\)
\(\Rightarrow x=10\)
Vậy \(x=10\).
(1/3+1/6).2^x.2^4-2^x=8192-1024
(1/3+1/6).2^x.2^4-2^x=7168
1/2.2^x.2^4-2^x=7168
1/2.2^x.(2^4-1)=7168
1/2.2^x.(8-1)=7168
1/2.2^x.7=7168
1/2.2^x=7168:7
1/2.2^x=1024
2^x=1024:1/2
2^x=2048
2^x=2^11
x=11
vậy x=11
\(x=\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}\)
\(x=\frac{1}{1}-\frac{1}{5}=\frac{4}{5}\)
\(\Rightarrow2^x\left(\frac{1}{2}+4\right)=288\Rightarrow2^x.\frac{9}{2}=288\Rightarrow2^x=64=2^6\Rightarrow x=6\)
\(\)\(\left(\frac{1}{2}+4\right).2^x=288\)
\(\frac{9}{2}.2^x=288\)
\(2^x=64\)
\(2^x=2^6\)
=> x=6