Question

If a+b+C =9 and ab+bc+ca=40 find a2+b2+c2

Answer 1

Hey mate!!
Here's your answer ^-^

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

9^2 = a^2+b^2+c^2 +2*40

81 = a^2+b^2+c^2 + 80

a^2+b^2+c^2 = 81-80
that's 1....

Hope this helps..☺☺

Answer 2

Answer is 1
a + b + c = 9 and ab + bc + ca = 40

We know that,

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

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

⇒ a 2 + b 2 + c 2 = (9)2 – 2 × 40 = 81 – 80 = 1 [a + b + c = 9 and ab + bc + ca = 40]

Thus, the value of a 2 + b 2 + c 2 is 1.