Respuesta :

Step-by-step explanation:

  • a+b+c=0
  • b+c=(-a) (SQUARING both the sides)
  • (b+c)²=(-a)²
  • (b²+c²+2bc)=a²
  • 2bc=a²-b²-c²

HENCE PROVED

-b²-c²=2bc

Step-by-step explanation:

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