Question

Daca a+b=12 si a-b=5, atunci a la puterea a 2 - b la puterea a 2 = ?

Answer 1

a^2 - b^2= (a+b)*(a-b)= 12*5 = 60

Answer 2

a+b=12. a-b=5 a= 5+ b. 5+b+b= 12 rez ca 2b= 12-5= 7. b = 7/2= 3,5 si a= 5+ 3,5= 8,5. (8,5)^2- ( 3,5)^2 = 72,25 - 12,25 = 60