Question

if(a+b+c)2=26,a2+b2+c2=13 then ab+bc+ac is​

Answer 1

Answer:

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Step-by-step explanation:

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

(a + b + c)² = 13 + 2(6) 

(a + b + c)² = 25 

a + b + c = 5 or -5 

a³ + b³ + c³ - 3abc = (a + b + c)(a² + b² + c² - ab - bc - ac) 

when (a + b + c = 5), 

a³ + b³ + c³ - 3abc 

= (5)(13 - 6) 

= (5)(7) 

= 35 

when (a + b + c = -5), 

a³ + b³ + c³ - 3abc 

= (-5)(13 - 6) 

= (-5)(7) 

= -35