Question

Alguien que me haga está función cuadratica paso a paso?
$3x {}^{2} + 15x - 42$
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Answer 1

SOLUCIÓN

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                         $Sea\:la\:ecuaci\'on\:cuadr\'atica:\\\\\\ax^2+bx+c=0\\\\\\Por\:f\'ormula\:general\:tenemos\:que:\\\\\\\mathrm{\boxed{x_{1,2}=\dfrac{-b\pm \sqrt{b^2-4ac}}{2a}}}\\\\\\Del\:problema:\\\\\\a=3,b=15,c=-42\\\\\\ Entonces\:reemplazamos\\\\\\x_{1,2}=\dfrac{-b\pm \sqrt{b^2-4ac}}{2a}\\\\\\x_{1,2}=\dfrac{-(15)\pm \sqrt{(15)^2-[4(3)(-42)]}}{2(3)}\\\\\\x_{1,2}=\dfrac{-15\pm \sqrt{225-(-504)}}{6}\\\\\\x_{1,2}=\dfrac{-15\pm \sqrt{729}}{6}\\\\\\x_{1,2}=\dfrac{-15\pm27}{6}$

                       $\Rightarrow\:x_{1}=\dfrac{-15+27}{6}\\\\\\x_{1}=\dfrac{12}{6}\\\\\\\boxed{\boldsymbol{x_{1}=2}}\\\\\\\Rightarrow\:x_{2}=\dfrac{-15-27}{6}\\\\\\x_{2}=\dfrac{-42}{6}\\\\\\\boxed{\boldsymbol{x_{2}=-7}}$