Question

If a+b+c = 7, ab + bc +ca = 20, Find a² + b² +c²​

Answer 1

Answer:

= (a+b+c)² = a² + b² + c² + 2 (ab) + (bc) + (ca)

= 7² = a²+ b²+ c²+ 2 × 20

= 49 = a²+ b²+ c²+ 40

= 49 - 40 = a²+ b²+ c²

= 9 = a²+ b²+ c²

answer = 9

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