Question

Cho tỉ lệ thức \(\dfrac{a}{b}=\dfrac{c}{d}\). Chứng minh: \(\dfrac{3a^2+5ac}{3a^2-5ac}=\dfrac{3b^2+5bd}{3b^2-5bd}\)

Ai nhanh mình tick cho nhé

Answer 1

Đặt a/b=c/d=k

=>a=bk; c=dk

\(\dfrac{3a^2+5ac}{3a^2-5ac}=\dfrac{3b^2k^2+5\cdot bk\cdot dk}{3b^2k^2-5\cdot bk\cdot dk}=\dfrac{3b^2k^2+5bdk^2}{3b^2k^2-5bdk^2}=\dfrac{3b^2+5bd}{3b^2-5bd}\)