Question

If l+m+n=15, lm+mn+nl=85, find the value of l²+m²+n².​

Answer 1

Step-by-step explanation:

${(l + m + n)}^{2} = {l}^{2} + {m}^{2} + {n}^{2} + 2lm + 2mn+ 2nl$

${l}^{2} + {m}^{2} + {n}^{2} = {(l + m + n)}^{2} - 2lm - 2mn - 2nl$

$= {(l + m + n)}^{2} - 2(lm - mn - nl)$

$= ( {15}^{2} ) - 2(85)$

$= 225 - 170$

$= 55$

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Answer 2

Step-by-step explanation:

The answer of this question is:

${15}^ {2} - 85 \\ 225 - 85 \\ 140$