How do you solve $v^2+ 10v - 21 = 0$ by completing the square?

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Answer 1 · 2015-05-02T22:06:47

$y = v^2 + 10.v - 21 = 0$

$y = v^2 + 10v + 25 - 25 - 21 = 0$

(v + 5)^2 = 46

$v + 5 = sqr46 -> v = -5 + sqr46$
$v + 5 = -sqr46 -> v = -5 - sqr46$

How do you solve v^2+ 10v - 21 = 0v^2+ 10v - 21 = 0 by completing the square?