Question

Si a b = 70. Calcular c en: \frac{a}{3}=\frac{b}{7}=\frac{c}{12} !

Answer 1

$ab=70 \quad ,\quad \frac{a}{3}=\frac{b}{7}=\frac{c}{12}\\ \\De \quad \frac{a}{3}=\frac{b}{7} \quad obtenemos \quad b=\frac{7}{3}a\\ \\ab=70 =a( \frac{7}{3}a)\\ 70=\frac{7}{3}a^2\\ \\a^2 =\frac{70 \times 3}{7}=30\\ \\a=\sqrt{30}\\ \\De \quad \frac{a}{3}=\frac{c}{12} \quad obtenemos \quad c=\frac{12}{3}a=4a\\ \\c=4\sqrt{30}$