Question

if a+b+c=9 and ab+bc+ca=26,find a^2+b^2+c^2

Answer 1

a+b+c=9 and ab+bc+ca=26,find a^2+b^2+c^2 We know that (a+b+c)^2=a^2+b^2+c^2+2 (ab+bc+ca) Now (9)^2=a^2+b^2+c^2+2 ×26 Or 81=a^2+b^2+c^2+52 Or 81-52=a^2+b^2+c^2 So A^2+B^2+C^2= 29