Question

if a+b+c=8 and a²+b²+c²=30,find the value of ab+bc+ca​

Answer 1

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Answer 2

Answer:

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Step-by-step explanation:

Given : a+b+c=8 and  a²+b²+c²=30

To find: value of (ab + bc + ca)

We know that,

(a+b+c)² =a²+b²+c² + 2 (ab+bc+ca)

Substituting the values, we get,

(8)² = 30 + 2 (ab+bc+ca)

64 = 30 + 2 (ab+bc+ca)

64 - 30 = 2 (ab+bc+ca)

34 = 2 (ab+bc+ca)

ab+bc+ca = 34 / 2

ab+bc+ca = 17

Hence, the required value of (ab+bc+ca) is 17.