Question

Me ajuda aq!!
Se (a - b)² - (a + b)² = -36, qual o valor de ab?

Answer 1

Resposta:

( a - b ) ² - ( a + b )²

(a)² -2.(a).(b) +(b) ² - [(a)² +2.(a).(b) +(b)²]

a² -2ab +b²  -[a² +2ab +b²]

a² -2ab +b² -a² -2ab -b²

a² -a² -2ab -2ab +b² -b²    cancela a² com -a²  e b² com -b²  

-4ab