Question

ifa2+b2+c2 =280 and ab+bc+ca=9/2,then find the value of (a+b+c)^2

Answer 1

Now (a+b+c)^2 = (a+b+c)(a+b+c) = a^2+ab+ca+ab+b^2+bc+ca+bc+c^2
=a^2+b^2+c^2+2(ab+bc+ca)
=280 +2(9/2) = 280 + 9 = 289 using given quantities
Answer: 289