Question

if a+b+c=13,a² +b² +c² =69 then ab+bc+ca=?

Answer 1

Answer:

50

Step-by-step explanation:

(a+b+c)2=a2+b2+c2+2(ab+bc+ca)  

2(ab+bc+ca)=(a+b+c)2−(a2+b2+c2)

=169−69=2(ab+bc+ca)  

=2(ab+bc+ca)=100/2

=50

Answer 2

Solution

Given :-

• a + b + c = 13 ---------(1)
• a² + b² + c² = 69------(2)

Find :-

• Value of ( ab + bc + ca)

Explanation

Using Formula

★ ( a+b+c)² = a²+b²+c²+2(ab+bc+ca)

Keep Value by equ(1) & equ(2)

==> 13² = 69 + 2(ab+bc+ca)

==> 2(ab+bc+ca) = 169 - 69

==> 2(ab+bc+ca) = 100

==> (ab+bc+ca) = 100/2

==> (ab+bc+ca) = 50

Hence

• Value of (ab+bc+ca) be 50

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