Question

1. If a : b = c : d, prove that :
(i) 5a + 7b : 5a – 7b = 5c + 7d : 5c – 7d.​

Answer 1

Answer:

$\frac{a}{b} = \frac{c}{d} \\ (Multiply \: by \: \frac{5}{7} \: on \: both \: sides) \\ = > \frac{5a}{7b} = \frac{5c}{7d} \\ (By \: componendo \: and \: dividendo) \\ = > \frac{5a + 7b}{5a - 7b} = \frac{5c + 7d}{5c - 7d}$