Răspunsuri

2014-09-17T18:15:40+03:00
2014-09-17T18:19:05+03:00
Folosim formula:
(a + b)² - a² - b² = + 2ab +  - a² - b² = 2ab

=> (7/5 + 3/5)²- (7/5)²-(3/5)² = 2 * (7/5) * (3/5) = 42 / 25