Question

DAU COROANA!determina daca x apartine nr reale pt care sunt adevarate egalitatile:a) x(x+1)=x+2 si b) (x+3)(x-3)=5-(x+2)(x-2)

Answer 1

a)x(x+1)=x+2
   x²+x=x+2  |-x
   x²=2
   x=√2∈R

b)(x+3)(x-3)=5-(x+2)(x-2) 
   x²-9=5-(x²-4)
   x²-9=5-x²+4
   x²-9=9-x²
   x²+x²=9+9
  2x²=18
  x²=9
  x={3, -3)
  x∈R