Question

If a+b+c=9 and ab+bc+can=26 find a^2+b^2+c^2

Answer 1

Hello friend  :-) 

your question is  a+b+c=9 , ab+bc+can=26 and we need to find  a^2+b^2+c^2 :-) 

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as we know that :=} 

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

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

now  (a+b+c) => 9  and  (ab+bc+ca) => 26 

put these values in the equation :-) 
a²+b²+c² = >   ( a+b+c) ²    - 2 ( ab + bc +ca )  to find a²+b²+c²

a²+b²+c² => 9^2  - 2 (26) 

a²+b²+c² => 81-52 

so we got the value of a²+b²+c² => 29 

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Hope this helps you !

@engineer gopal khandelwal doing b-tech from IIT roorkey :-) 

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Answer 2

Hi friend!!

a+b+c = 9

ab+bc+ca = 26

We know

(a+b+c) ² = a²+b²+c² +2(ab+bc+ca)

a²+b²+c² = (a+b+c)² - 2(ab+bc+ca)

→ = 9²-2(26)

→ = 81 - 52

→ = 29

Hope it helps...