1. cho \(\dfrac{a}{b}\) = \(\dfrac{d}{c}\)
a) \(\dfrac{a+b}{b}\) = \(\dfrac{c+d}{d}\)
b) \(\dfrac{a}{a-b}\) = \(\dfrac{c}{c-d}\)
c) \(\dfrac{2a-5b}{2c-5d}\) = \(\dfrac{3a+4b}{3c+4d}\)
d) \(\dfrac{a^2-c^2}{b^2-d^2}\) = \(\dfrac{ac}{bd}\)
HELP ME !!! MK SẼ TICK CHO