The Total solution for NCERT class 6-12
a + b + c = 9, ab + bc + ca = 40Squaring both sides,(a + b + c)2 = (9)2a2 + b2 + c2 + 2{ab + bc+ ca) = 81⇒ a2 +b2 + c2 + 2 x 40 = 81⇒ a2 + b2 + c2 + 80 = 81a2 + b2 + c2 = 81 – 80 = 1