Question

Calculați :
$\frac{2}{3 \times 5} + \frac{2}{5 \times 7} + \frac{3}{7 \times 10} + \frac{2}{10 \times 12}$
.
VA ROG AJUTATI-MĂ.
VREAU REZOLVAREA COMPLETĂ SI CORECTA!!!

Answer 1

Imnultim nr de la numitor, dupa care aducem fractiile la numitorul comun 420.
(2/15)+(2/35)+(3/70)+(1/60)=
(56+24+18+7)/420=
105/420=1/4

Answer 2

$\frac{2}{3 \times 5} + \frac{2}{5 \times 7} + \frac{3}{7 \times 10} + \frac{2}{10 \times 12} \\ \\ \frac{2}{15} + \frac{2}{35} + \frac{3}{70} + \frac{2}{120} \\ \\ \frac{2}{15} + \frac{2}{35} + \frac{3}{70} + \frac{1}{60} = \frac{105}{420} = \frac{1}{4}$