Solve $x^{2} + 8 x + 15 = 0$ by method of completing square.

x = 3, - 5

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x = - 3, - 5

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x = 3, 5

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x = - 3, 5

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Solution

The correct option is D $x = - 3, - 5$
Given:
$x^{2} + 8 x + 15 = 0$
$x^{2} + 8 x = - 15$
Add $16$ on both sides,
$x^{2} + 8 x + 16 = - 15 + 16$
$x^{2} + 2 \times 4 x + 4^{2} = 1$
$(x + 4)^{2} = 1$
$x + 4 = \pm 1$
Hence, $x = - 4 + 1 = - 3$ or $x = - 4 - 1 = - 5$

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x^{2} - 8 x + 15 = 0

x^{2} + 8 x + 5

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Solve each of the following equations by using the method of completing the square:
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