Bài 1:
Dễ rồi nhé bn tự lm đi nha
Bài 2:
\(a)\dfrac{5a+3b}{5a-3b}=\dfrac{5a+3d}{5c-3d}\Leftrightarrow\dfrac{5bk+3b}{5bk-3b}=\dfrac{5dk+3d}{5dk-3d}\)
Xét VT \(\dfrac{5bk+3b}{5bk-3b}=\dfrac{b\left(5k+3\right)}{b\left(5k-3\right)}=\dfrac{5k+3}{5k-2}\left(1\right)\)
Xét VP \(\dfrac{5dk+3d}{5dk-3d}=\dfrac{d\left(5k-3\right)}{d\left(5k-3\right)}=\dfrac{5k+3}{5k-3}\left(2\right)\)
Từ \(\left(1\right)\) và \(\left(2\right)\rightarrowđpcm\)
\(b)\dfrac{7a^2+3ab}{11a^2-8b^2}=\dfrac{7c^2+3cd}{11c^2-8d^2}\)
\(\left\{{}\begin{matrix}b,d\ne0\\11a^2\ne8b^2\\11c^2\ne8d^2\end{matrix}\right.\)
\(\dfrac{a}{b}=\dfrac{c}{d}\Rightarrow\left(\dfrac{a^2}{b^2}=\dfrac{c^2}{d^2}\right)\Rightarrow\dfrac{7a^2+3ab}{11a^2-8b^2}=\dfrac{7.\dfrac{a^2}{b^2}+3\dfrac{a}{b}}{11.\dfrac{a^2}{b^2}-8}=\dfrac{7.\dfrac{c^2}{d^2}+3\dfrac{c}{d}}{11.\dfrac{c^2}{d^2}-8}=\dfrac{7c^2+3cd}{11c^2-8d^2}=VP\)
Chúc bạn học tốt!
