Question

biết 9x² + 4y² = 20xy và 2y<3x<0

khi đó giá trị của A = \(\dfrac{3x-2y}{3x+2y}\) là

Answer 1

= \(\dfrac{1}{2}\)nha

Answer 2

\(\dfrac{3x-2y}{3x+2y}=\dfrac{\left(3x-2y\right)^2}{\left(3x+2y\right)^2}=\dfrac{9x^2+4y^2-12xy}{9x^2+4y^2+12xy}=\dfrac{1}{4}\)

thay từ đề vào ok

Answer 3

\(\left\{{}\begin{matrix}2y< 3x< 0\\\left\{{}\begin{matrix}3x-2y>0\\3x+2y< 0\end{matrix}\right.\end{matrix}\right.\) \(\left\{{}\begin{matrix}A^2=\dfrac{12xy}{32xy}=\dfrac{12}{32}=\dfrac{3}{8}\\A< 0\Rightarrow A=-\sqrt{\dfrac{3}{8}}\end{matrix}\right.\)

Answer 4

Nhầm:

\(\left\{{}\begin{matrix}2y< 3x< 0\\A< 0\end{matrix}\right.\) \(\left\{{}\begin{matrix}A^2=\dfrac{8xy}{32xy}=\dfrac{8}{32}=\dfrac{1}{4}\\A< 0\Rightarrow A=-\sqrt{\dfrac{1}{4}}=-\dfrac{1}{2}\end{matrix}\right.\)