Question

Sendo |u+v|=7 e |u-v|=5, calcule u.v

Answer 1

u+v = 7
u-v = 5
u+v+u-v = 7+5
u+u = 12 (corta +V com - V)
2u=12
u= 6
u+v = 7
6+v=7
v = 7-6
v = 1

6.1 = 6.