Question

các bạn giúp mik vs

Answer 1

a) ĐKXĐ: \(x\ge0\)

\(\Leftrightarrow\dfrac{1}{2}\sqrt{x}+\dfrac{9}{4}=\dfrac{5}{2}\\ \Leftrightarrow\dfrac{1}{2}\sqrt{x}=\dfrac{1}{4}\\ \Leftrightarrow\sqrt{x}=\dfrac{1}{2}\\ \Leftrightarrow x=\dfrac{1}{4}\)

b) \(\dfrac{x}{2}=\dfrac{y}{3}\Rightarrow\dfrac{x}{10}=\dfrac{y}{15}\)

\(\dfrac{y}{5}=\dfrac{z}{4}\Rightarrow\dfrac{y}{15}=\dfrac{z}{12}\)

\(\Rightarrow\dfrac{x}{10}=\dfrac{y}{15}=\dfrac{z}{12}\)

Áp dụng t/c dtsbn ta có:

\(\dfrac{x}{10}=\dfrac{y}{15}=\dfrac{z}{12}=\dfrac{x-y+z}{10-15+12}=-\dfrac{49}{7}=-7\)

\(\dfrac{x}{10}=-7\Rightarrow x=-70\\ \dfrac{y}{15}=-7\Rightarrow y=-105\\ \dfrac{z}{12}=-7\Rightarrow z=-84\)

Answer 2

\(\dfrac{1}{2}\sqrt{x}+\sqrt{\dfrac{81}{16}=\dfrac{5}{2}}\)

\(\dfrac{1}{2}\sqrt{x}+\dfrac{9}{4}=\dfrac{5}{2}\)

\(\dfrac{1}{2}\sqrt{x}=\dfrac{5}{2}-\dfrac{9}{4}\)

\(\dfrac{1}{2}\sqrt{x}=\dfrac{1}{4}\)

\(\sqrt{x=}\dfrac{1}{4}:\dfrac{1}{2}\)

\(\sqrt{x}=\dfrac{1}{2}\)

x=\(\dfrac{1}{4}\)