I have an inequality and I don't know if I need to use the quadratic formula or not...it's like this: x^2 + 8x - 4 < 0 Can't be factored with decomposition so yeahhhh, any suggestions?
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Originally Posted by cjh824 x^2 + 8x - 4 < 0 Can't be factored with decomposition so With real roots it can always be factored. $\displaystyle x^2 + 8x - 4 = \left[ {x - \left( {\frac{{ - 8 + \sqrt {80} }} {2}} \right)} \right]\left[ {x - \left( {\frac{{ - 8 - \sqrt {80} }} {2}} \right)} \right]$
$\displaystyle x^{2}+8x-4<0\implies (x+4)^{2}<20\implies -2\sqrt{5}-4<x<2\sqrt{5}-4.$
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