Question

\(\frac{3x}{7y}\sqrt{\frac{49y^2}{9x^2}\left(x>0,y< 0\right)}\)

Answer 1

\(\frac{3x}{7y}\sqrt{\frac{49y^2}{9x^2}}\) \(=\frac{3x}{7y}|\frac{7y}{3x}|\left(1\right)\)

mà \(x>0,y< 0\)

=>\(\left(1\right)\) = \(\frac{3x.\left(-7y\right)}{7y.3x}=-1\)

chúc bn học tốt

Answer 2

\(\frac{3x}{7y}\sqrt{\frac{49y^2}{9x^2}}\)

\(=\frac{3x}{7y}\sqrt{\frac{\left(7y\right)^2}{\left(3x\right)^2}}\)\(=\frac{3x}{7y}\cdot\frac{\left|7y\right|}{\left|3x\right|}\)

mak ta có \(x>0;y< 0\) 

 \(\Rightarrow\frac{3x}{7y}\cdot\frac{-7y}{3x}\)\(\Rightarrow\frac{3x\cdot-7y}{7x\cdot3x}=\left(-1\right)\)
\(\Rightarrow\frac{3x}{7y}\sqrt{\frac{49y^2}{9x^2}}=\left(-1\right)\)