Question

If a+b+c =6 and ab+bc+ca =15 then find the value of a square + b square + c square

Answer 1

As we know (a+b+c)^2=a^2+b^2+c^2+2(ab+bc+ca)--------1
so putting the value of a+b+c=6 and ab+bc+ca=15 in eq1
so
36=a^2+b^2+c^2+2(15)
solving we get
a^2+b^2+c^2=6

hope this helps you.