Question

Answer 1

a: \(\frac{a}{b}=\frac{126}{135}\)

=>\(\frac{a}{b}=\frac{14}{15}\)

=>\(\frac{a}{14}=\frac{b}{15}\)

Đặt \(\frac{a}{14}=\frac{b}{15}=k\)

=>a=14k; b=15k

Ta có: \(126=3^2\cdot2\cdot7;135=3^3\cdot5\)

Do đó: BCNN(126;135)\(=2\cdot3^3\cdot5\cdot7=1890\)

mà BCNN(a;b)=1890

và \(\frac{a}{b}=\frac{126}{135}\)

nên a=126; b=135

=>\(\frac{a}{b}=\frac{126}{135}\)

b: \(\frac{a}{b}=\frac{60}{108}\)

=>\(\frac{a}{b}=\frac59\)

ƯCLN(a;b)=180

=>\(a=5\cdot180=900;b=9\cdot180=1620\)

Vậy: \(\frac{a}{b}=\frac{900}{1620}\)