Question

\(\frac{x-1}{12}=\frac{4}{x+1}\)

\(\frac{x}{4}=\frac{10}{x+3}\)

Answer 1

Bạn dựa vào :

\(\frac{a}{b}=\frac{c}{d}\Leftrightarrow ad=bc\)

Answer 2

a) => (x - 1)(x + 1) = 4.12 = 6.(2.4) = 6.8

=> x - 1 = 6 => x = 6 - 1 = 7

 

Answer 3

b) => x(x + 3) = 4.10 = 5.(2.4) = 5.8

=> x = 5