Question

Chứng minh rằng: Nếu \(\dfrac{a}{b}=\dfrac{c}{d}\) thì:

\(\dfrac{7a^2+3ab}{11a^2-8b^2}\)= \(\dfrac{7c^2+3cd}{11c^2-8d^2}\)

Giúp mk vs! Mk tick luôn!

Answer 1

Đặt:

\(\dfrac{a}{b}=\dfrac{c}{d}=k\Leftrightarrow\left\{{}\begin{matrix}a=bk\\c=dk\end{matrix}\right.\)

\(\left\{{}\begin{matrix}\dfrac{7a^2+3ab}{11a^2-8b^2}=\dfrac{7b^2k^2+3b^2k}{11b^2k^2-8b^2}=\dfrac{b^2\left(7k^2+3k\right)}{b^2\left(11k^2-8\right)}=\dfrac{7k^2+3k}{11k^2-8}\\\dfrac{7c^2+3cd}{11c^2-8d^2}=\dfrac{7d^2k^2+3d^2k}{11d^2k^2-8d^2}=\dfrac{d^2\left(7k^2+3k\right)}{d^2\left(11k^2-8\right)}=\dfrac{7k^2+3k}{11k^2-8}\end{matrix}\right.\)Ta có điều phải chứng minh

Answer 2

Đợi cj lát!!!Mai e hok à?