4.4x=16
giúp mình với
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Ta có : \(\left\{{}\begin{matrix}2^{24}=\left(2^3\right)^8=8^8\\3^{16}=\left(3^2\right)^8=9^8\end{matrix}\right.\)
Thấy : \(9>8\)
\(\Leftrightarrow9^8>8^8\)
\(\Leftrightarrow3^{16}>2^{24}\)
Vậy ...
\(0,05+5-\dfrac{1}{20}=0,05+5-0,05=5\)
\(\dfrac{6}{15}-\dfrac{7}{8}+3+\dfrac{3}{5}-\dfrac{2}{16}=\dfrac{2}{.5}-\dfrac{7}{8}+3+\dfrac{3}{5}-\dfrac{1}{8}=1-1+3=3\)
a) \(0.05+5-\dfrac{1}{20}=\dfrac{1}{20}+5-\dfrac{1}{20}=5\)
b) \(\dfrac{6}{15}-\dfrac{7}{8}+3+\dfrac{3}{5}-\dfrac{2}{16}=1-1+3=3\)
Áp dụng t/c dãy tỉ số bằng nhau:
a.
\(\dfrac{x}{3}=\dfrac{y}{5}=\dfrac{2x}{6}=\dfrac{4y}{20}=\dfrac{2x+4y}{6+20}=\dfrac{28}{26}=\dfrac{14}{13}\)
\(\Rightarrow\left\{{}\begin{matrix}x=3.\dfrac{14}{13}=\dfrac{52}{13}\\y=5.\dfrac{14}{13}=\dfrac{70}{13}\end{matrix}\right.\)
(Em có nhầm đề 26 thành 28 ko nhỉ, số xấu quá)
b.
\(4x=5y\Rightarrow\dfrac{x}{5}=\dfrac{y}{4}=\dfrac{3x}{15}=\dfrac{-2y}{-8}=\dfrac{3x-2y}{15-8}=\dfrac{35}{7}=5\)
\(\Rightarrow\left\{{}\begin{matrix}x=5.5=25\\y=4.2=20\end{matrix}\right.\)
c.
\(\dfrac{x}{-3}=\dfrac{y}{-7}=\dfrac{2x}{-6}=\dfrac{4y}{-28}=\dfrac{2x+4y}{-6-28}=\dfrac{68}{-34}=-2\)
\(\Rightarrow\left\{{}\begin{matrix}x=-3.\left(-2\right)=6\\y=-7.\left(-2\right)=14\end{matrix}\right.\)
d.
\(\dfrac{x}{2}=\dfrac{y}{-3}=\dfrac{z}{4}=\dfrac{4x}{8}=\dfrac{-3y}{9}=\dfrac{-2z}{-8}=\dfrac{4x-3y-2z}{8+9-8}=\dfrac{16}{9}\)
\(\Rightarrow\left\{{}\begin{matrix}x=2.\dfrac{16}{9}=\dfrac{32}{9}\\y=-3.\dfrac{16}{9}=-\dfrac{48}{9}\\z=4.\dfrac{16}{9}=\dfrac{64}{9}\end{matrix}\right.\)
\(4\cdot4^x=16\)
=> \(4^{x+1}=4^2\)
=> \(x+1=2\)
=> \(x=1\)
x=1 nhé