Question

If a2+b2+c2=20 and a + b + c = 0, then find the value of ab+bc+ca.

Answer 1

02-20/2

This is answer to ur solution

Answer 2

Answer:

value of (ab+bc+ca)  = -10

Step-by-step explanation:

By the arithmetic identity

$(a+ b + c)^{2}  = a^{2} + b^{2} + c^{2} + 2 ( ab + bc + ac)$

Now, here (a+ b+c) = 0

and,     $a^{2}  + b^{2}  + c^{2}  = 20$

Now, putting the above values in the identity,

we get $(0)^{2}  = 20 +  2(ab + bc + ac)$

⇒ 2(ab + bc + ac)  = -20

or, (ab + bc + ac)  = -20 / 2 = -10

Hence, value of (ab+bc+ca)  = -10