Question

6. Find a² +b²+c² if a+b+c=9 and ab +bc +ca = 9​

Answer 1

Answer:

63

Step-by-step explanation:

a^2 + b^2 + c^2

we know that ,

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

⇒(a+ b+ c)  ^2 =a^2 +b  ^2  +c  ^2  +2(ab +bc+ ca).

putting the values ,

(9)^2 = a^2 + b^2 + c^ + 2(9)

81 = a^2 + b^2 + c^2 + 18

therefore ,

a^2 + b^2 + c^2 = 81 - 18

= 63