Question

quanto vale esta soma?

1/1.2+1/2.3+1/3.4+1/4.5+1/5.6+1/6.7+1/7.8=?

Answer 1

$\frac{1}{1} . 2 + \frac{1}{2} . 3 + \frac{1}{3} . 4 + \frac{1}{4} . 5 + \frac{1}{5} . 6 + \frac{1}{6} . 7 + \frac{1}{7} . 8$
$\frac{1}{1} . \frac{2}{1} + \frac{1}{2} . \frac{3}{1} + \frac{1}{3} . \frac{4}{1} + \frac{1}{4} . \frac{5}{1} + \frac{1}{5} . \frac{6}{1} + \frac{1}{6} . \frac{7}{1} + \frac{1}{7} . \frac{8}{1}$

MMC = {1, 2, 3, 4, 5, 6, 7} = 420

$\frac{420.840+210.1260+140.1680+105.2100+84.2520+70.2940+60.3360}{420}$
$\frac{1692180}{420}$
$4029$