Q5 of 274 Page 91

If (a + b + c) = 8 and (ab + bc + ca) = 19, find (a2 + b2 + c2)

It is given in the question that,

(a + b + c) = 8


And, (ab + bc + ca) = 19


We know that,


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


∴ (8)2 = a2 + b2 + c2 + 2 × 19


64 = a2 + b2 + c2 + 38


64 – 38 = a2 + b2 + c2


a2 + b2 + c2 = 26


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