If a + b + c = 9 and ab + bc + ca = 23, then a2+b2+c2=
35
58
127
none of these
a+b+c=9,ab+bc+ca=23Squaring,(a+b+c)2=(9)2a2+b2+c2+2(ab+bc+ca)=81⇒ a2+b2+c2+2×23=81⇒ a2+b2+c2+46=81⇒ a2+b2+c2=81−46=35