Question

☺ It a² +b² c²-20 and a+b+c=0 find ab+bc+ca
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Answer 1

Answer:

ab+bc+ca=-10

Step-by-step explanation:

use formula of (a+b+c)²

Answer 2

Answer:

-10 is the answer

I will tell you how it came.

Step-by-step explanation:

Given;

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

$a + b + c = 0$

There's a formula that,

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

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

I will substitute the values in the equation

${(0)}^{2} = 20 + 2(ab + bc + ca)$

$- 20 = 2(ab + bc + ca)$

$- 10 = ab + bc + ca$

If you like the process please comment.