Question

a+b+c=12 a2+b2+c2=150 then find 3( ab+ bc+ ca )​

Answer 1

Answer:

-9

Step-by-step explanation:

a+b+c = 12

a²+b²+c² = 150

Now ,

(a+b+c)² = a²+b²+c²+2(ab+bc+ca)

12² = 150 + 2(ab+bc+ca)

144 = 150 + 2(ab+bc+ca)

-6 = 2(ab+bc+ca)

-3 = ab+bc+ca

Then, according to the question-

3(ab+bc+ca) = 3 * (-3)

= -9