\(5^{x+2}-5^x=3.10^3\)
Giải nhanh nha
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\(5^{x+2}-5^x=3.10^3\)
\(\Rightarrow5^x\left(5^2-1\right)=3000\)
\(\Rightarrow5^x.24=3000\Rightarrow5^x=125=5^3\)
\(\Rightarrow x=3\)
\(5^{x+2}-5^x=3\cdot10^3\)
\(\Leftrightarrow5^x\cdot24=3000\)
\(\Leftrightarrow x=3\)
\(a,3^{x+2}=7\\ \Leftrightarrow x+2=log_37\\ \Leftrightarrow x=log_37-2\approx-0.229\)
\(b,3\cdot10^{2x+1}=5\\ \Leftrightarrow10^{2x+1}=\dfrac{5}{3}\\ \Leftrightarrow2x+1=log\left(\dfrac{5}{3}\right)\\ \Leftrightarrow2x=log\left(\dfrac{5}{3}\right)-1\\ \Leftrightarrow x=\dfrac{1}{2}\cdot log\dfrac{5}{3}-\dfrac{1}{2}\\ \Leftrightarrow x\approx-0,389\)
a).\(\dfrac{x}{15}\)=\(\dfrac{4}{3}\)\(\Leftrightarrow\)x.3=15.4\(\Leftrightarrow\)3x=60\(\Leftrightarrow\)x=20
b)x:\(\dfrac{4}{3}\)=\(\dfrac{5}{6}\)\(\Leftrightarrow\)\(\dfrac{3x}{4}=\dfrac{5}{6}\)\(\Leftrightarrow\)3x.6=4.5\(\Leftrightarrow\)18x=20\(\Leftrightarrow\)\(\dfrac{10}{9}\)
c)\(\dfrac{7}{2}\)-x=\(\dfrac{5}{6}\)\(\Leftrightarrow\)\(\dfrac{7}{2}-\dfrac{2x}{2}\)=\(\dfrac{5}{6}\)\(\Leftrightarrow\)\(\dfrac{7-2x}{2}\)=\(\dfrac{5}{6}\)\(\Leftrightarrow\)(7-2x).6=2.5\(\Leftrightarrow\)42-12x=10
\(\Leftrightarrow\)-12x=-32\(\Leftrightarrow\)x=\(\dfrac{8}{3}\)
1. \(x^{100}=x\)
\(TH1:x=0\)
Khi đó \(0^{100}=0\)
\(TH1:x\) ≠ \(0\)
Khi đó \(x^{100}=x\)
⇒\(x^{100}:x=1\)
⇒ \(x^{99}=1\)
⇒\(x=1\)
Vậy \(x\) ∈ \(\left\{0;1\right\}\)
\(\dfrac{1}{2}\times\dfrac{2}{3}\times\dfrac{3}{4}\times\dfrac{4}{5}\times\dfrac{5}{6}\times\dfrac{6}{7}\times\dfrac{7}{8}\times\dfrac{8}{9}\)
\(=\dfrac{1\times2\times3\times4\times5\times6\times7\times8}{2\times3\times4\times5\times6\times7\times8\times9}\)
\(=\dfrac{1}{9}\)
\(5^{x+2}-5^x=3.10^3\)
\(5^x\left(5^2-1\right)=3.1000\)
\(5^x.24=3000\)
\(5^x=3000:24\)
\(5^x=125\)
\(5^x=5^3\)
\(\Rightarrow x=3\)