Question

If a+b+c=10 and ab+bc+ca=31 Find the value of a²+b²+c²

Answer 1

(a+b+c) = 10

Square on both sides,
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by formula (a+b+c)^2 =a^2 +b^2 +c^2 +2(ab+bc+ca)
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Here,

a^2 +b^2 +c^2 +2(ab+bc+ca) = 10^2

put the given values,

a^2 +b^2 +c^2 +[2*31] = 100

a^2 +b^2+c^2 +62 = 100

a^2 +b^2 +c^2 = 100-62

a^2 +b^2 +c^2 = 38


 i hope this will help you


-by ABHAY

Answer 2

Hi friend
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Your answer
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Given that : - (a + b + c) = 10 and (ab + bc + ca) = 31.

To find : - Value of (a² + b² + c²)

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

=> (10)² = (a² + b² + c²) + (2 × 31)

=> a² + b² + c² = 100 - 62

=> a² + b² + c² = 38

HOPE IT HELPS