Question

If A+B+C=6 and A²+B²+C²=26 find the value of AB+BC+CA​

Answer 1

Answer:

(AB + BC + AC) = 5

Step-by-step explanation:

We know that,

A + B + C = 6

A² + B² + C² = 26

We must find,

AB + BC + AC

Now,

(A + B + C)² = A² + B² + C² + 2(AB + BC + AC)

(A + B + C)² = (A² + B² + C²) + 2(AB + BC + AC)

but we know that,

(A + B + C) = 6

(A² + B² + C²) = 26

Thus, Putting it in the equation we get,

6² = 26 + 2(AB + BC + AC)

36 = 26 + 2(AB + BC + AC)

36 - 26 = 2(AB + BC + AC)

10/2 = (AB + BC + AC)

Thus,

(AB + BC + AC) = 5

Hope it helped and you understood it........All the best