Question

If a+b+c=0 and asquare+bsquare+csquare=20, find ab+bc+ca
please give answers with formula​

Answer 1

Answer:

Given

$a + b + c = 0$

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

according to question

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

put all the given value to this formula

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

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

$\frac{ - 20}{2} = ab + bc + ca$

$ab + bc + ca = - 10$

I hope it is help for you