VA rog ma ajutati?
(7/5 + 3/5)²- (7/5)²-(3/5)²


Răspuns :

(10/5)^2-49/25-9/25 = 100/25-49/25-9/25=42/25
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