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प्रश्न
If a2 + b2 + c2 = 35 and ab + bc + ca = 23; find a + b + c.
उत्तर
We know that
( a + b + c )2 = a2 + b2 + c2 + 2( ab + bc + ca ) ....(1)
Given that, a2 + b2 + c2 = 35 and ab + bc + ca = 23
We need to find a + b + c :
Substitute the values of ( a2 + b2 + c2 ) and ( ab + bc + ca )
in the identity (1), we have
( a + b + c )2 = 35 + 2(23)
⇒ ( a + b + c )2 = 81
⇒ a + b + c = `+-sqrt81`
⇒ a + b + c = `+-9`
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