Question

[Go!Princess Precure]

Giup minh nhe

Answer 1

[Nguyễn Nam]

2)

a)\(\left|x+3\right|=3\)

\(\Leftrightarrow x+3=\pm3\)

\(\Leftrightarrow\left[{}\begin{matrix}x+3=3\\x+3=-3\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=3-3\\x=-3-3\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-6\end{matrix}\right.\)

Vậy x=0 ; x=-6

b) \(\dfrac{1}{9}.3^4.3^x=3^2\)

\(\Leftrightarrow\dfrac{1}{3^2}.3^2.3^2.3^x=3^2\)

\(\Leftrightarrow3^2.3^x=3^2\)

\(\Leftrightarrow3^{2+x}=3^2\)

\(\Leftrightarrow2+x=2\)

\(\Leftrightarrow x=2-2\)

\(\Leftrightarrow x=0\)

Vậy x=0

c) \(-4\dfrac{1}{3}:\dfrac{\sqrt{x}}{4}=4:\left(-0,3\right)\)

\(\Leftrightarrow\dfrac{-13}{3}:\dfrac{\sqrt{x}}{4}=\dfrac{-40}{3}\)

\(\Leftrightarrow\dfrac{\sqrt{x}}{4}=\dfrac{-13}{3}:\dfrac{-40}{3}\)

\(\Leftrightarrow\dfrac{\sqrt{x}}{4}=\dfrac{-13}{3}.\dfrac{-3}{40}\)

\(\Leftrightarrow\dfrac{\sqrt{x}}{4}=\dfrac{39}{120}=\dfrac{13}{40}\)

\(\Leftrightarrow\sqrt{x}.40=13.4\)

\(\Leftrightarrow\sqrt{x}.40=52\)

\(\Leftrightarrow\sqrt{x}=\dfrac{52}{40}=\dfrac{13}{10}\)

\(\Leftrightarrow x=\left(\dfrac{13}{10}\right)^2=\dfrac{169}{100}\)

Vậy \(x=\dfrac{169}{100}\)

Answer 2

[Nguyễn Nam]

3)So Sánh: \(3^{50}\) và \(5^{30}\)

\(3^{50}=3^{5.10}=\left(3^5\right)^{10}=243^{10}\)

\(5^{30}=5^{3.10}=\left(5^3\right)^{10}=125^{10}\)

Vì \(243>125\)

Nên \(243^{10}>125^{10}\)

Vậy \(3^{50}>5^{30}\)