Question

if a+b+c=15, ab+bc+ac=35, find a²+b²+c²​

Answer 1

Answer:

a+b+c=15

squaring both sides we get

a^2+b^2+c^2+2ab+2bc+2ca=225

a^2+b^2+c^2=225-2(ab+bc+ca)

, =225-2×35

=225-70

=155