Question

Se considera vectorii a=xi-2j si b= -i+yj. Determinati x,y care apartin multimii numerelor reale daca |a|=2radical din 10 si |b|=2. Dau coroana.

Answer 1

a = xi-2j

b = -i+yj

|a| = 10 => √(x²+2²) = 2√10 => x²+4 = 200

=> x² = 196 => x = ±14

|b| = 2 => √(1²+y²) = 2 => y²+1 = 4 => y² = 3 => y = ±√3

=> (x,y) = (±14, ±√3)