Question

if a+b+c=6 and a²+b²+c²=25; find ab+bc+ca​

Answer 1

Answer:

We have,

(a+b+c)²=a²+b²+c²+2(ab+bc+ca).

So,

15 2 =a²+b²+c²+2(25)225=a²+b²+c²+50

∴a²+b²+c²=225−50=175