Question

if a^2+b^2+c^2=30 and a+b+c=10,then find the value of ab+bc+ca​

Answer 1

Answer:

a+b+c)²=a²+b²+c²-2(ab+bc+ca)

100-30=-2(ab+bc+ca)

-35=ab+bc+ca

Answer 2

Answer:

35 is the correct answer.

formula used:

(a+b+c)² = a²+b²+c²+2ab+2bc+2ca