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x^2+5x+(3a+18)=0 la ecuación

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Solución

Ha introducido [src]
 2                     
x  + 5*x + 3*a + 18 = 0
$$\left(3 a + 18\right) + \left(x^{2} + 5 x\right) = 0$$
Solución detallada
Es la ecuación de la forma
a*x^2 + b*x + c = 0

La ecuación cuadrática puede ser resuelta
con la ayuda del discriminante.
Las raíces de la ecuación cuadrática:
$$x_{1} = \frac{\sqrt{D} - b}{2 a}$$
$$x_{2} = \frac{- \sqrt{D} - b}{2 a}$$
donde D = b^2 - 4*a*c es el discriminante.
Como
$$a = 1$$
$$b = 5$$
$$c = 3 a + 18$$
, entonces
D = b^2 - 4 * a * c = 

(5)^2 - 4 * (1) * (18 + 3*a) = -47 - 12*a

La ecuación tiene dos raíces.
x1 = (-b + sqrt(D)) / (2*a)

x2 = (-b - sqrt(D)) / (2*a)

o
$$x_{1} = \frac{\sqrt{- 12 a - 47}}{2} - \frac{5}{2}$$
$$x_{2} = - \frac{\sqrt{- 12 a - 47}}{2} - \frac{5}{2}$$
Teorema de Cardano-Vieta
es ecuación cuadrática reducida
$$p x + q + x^{2} = 0$$
donde
$$p = \frac{b}{a}$$
$$p = 5$$
$$q = \frac{c}{a}$$
$$q = 3 a + 18$$
Fórmulas de Cardano-Vieta
$$x_{1} + x_{2} = - p$$
$$x_{1} x_{2} = q$$
$$x_{1} + x_{2} = -5$$
$$x_{1} x_{2} = 3 a + 18$$
Gráfica
Respuesta rápida [src]
              ________________________________                                              ________________________________                                      
           4 /                 2         2        /atan2(-12*im(a), -47 - 12*re(a))\     4 /                 2         2        /atan2(-12*im(a), -47 - 12*re(a))\
           \/  (-47 - 12*re(a))  + 144*im (a) *cos|--------------------------------|   I*\/  (-47 - 12*re(a))  + 144*im (a) *sin|--------------------------------|
       5                                          \               2                /                                            \               2                /
x1 = - - - ------------------------------------------------------------------------- - ---------------------------------------------------------------------------
       2                                       2                                                                            2                                     
$$x_{1} = - \frac{i \sqrt[4]{\left(- 12 \operatorname{re}{\left(a\right)} - 47\right)^{2} + 144 \left(\operatorname{im}{\left(a\right)}\right)^{2}} \sin{\left(\frac{\operatorname{atan_{2}}{\left(- 12 \operatorname{im}{\left(a\right)},- 12 \operatorname{re}{\left(a\right)} - 47 \right)}}{2} \right)}}{2} - \frac{\sqrt[4]{\left(- 12 \operatorname{re}{\left(a\right)} - 47\right)^{2} + 144 \left(\operatorname{im}{\left(a\right)}\right)^{2}} \cos{\left(\frac{\operatorname{atan_{2}}{\left(- 12 \operatorname{im}{\left(a\right)},- 12 \operatorname{re}{\left(a\right)} - 47 \right)}}{2} \right)}}{2} - \frac{5}{2}$$
              ________________________________                                              ________________________________                                      
           4 /                 2         2        /atan2(-12*im(a), -47 - 12*re(a))\     4 /                 2         2        /atan2(-12*im(a), -47 - 12*re(a))\
           \/  (-47 - 12*re(a))  + 144*im (a) *cos|--------------------------------|   I*\/  (-47 - 12*re(a))  + 144*im (a) *sin|--------------------------------|
       5                                          \               2                /                                            \               2                /
x2 = - - + ------------------------------------------------------------------------- + ---------------------------------------------------------------------------
       2                                       2                                                                            2                                     
$$x_{2} = \frac{i \sqrt[4]{\left(- 12 \operatorname{re}{\left(a\right)} - 47\right)^{2} + 144 \left(\operatorname{im}{\left(a\right)}\right)^{2}} \sin{\left(\frac{\operatorname{atan_{2}}{\left(- 12 \operatorname{im}{\left(a\right)},- 12 \operatorname{re}{\left(a\right)} - 47 \right)}}{2} \right)}}{2} + \frac{\sqrt[4]{\left(- 12 \operatorname{re}{\left(a\right)} - 47\right)^{2} + 144 \left(\operatorname{im}{\left(a\right)}\right)^{2}} \cos{\left(\frac{\operatorname{atan_{2}}{\left(- 12 \operatorname{im}{\left(a\right)},- 12 \operatorname{re}{\left(a\right)} - 47 \right)}}{2} \right)}}{2} - \frac{5}{2}$$
x2 = i*((-12*re(a) - 47)^2 + 144*im(a)^2)^(1/4)*sin(atan2(-12*im(a, -12*re(a) - 47)/2)/2 + ((-12*re(a) - 47)^2 + 144*im(a)^2)^(1/4)*cos(atan2(-12*im(a), -12*re(a) - 47)/2)/2 - 5/2)
Suma y producto de raíces [src]
suma
         ________________________________                                              ________________________________                                                  ________________________________                                              ________________________________                                      
      4 /                 2         2        /atan2(-12*im(a), -47 - 12*re(a))\     4 /                 2         2        /atan2(-12*im(a), -47 - 12*re(a))\         4 /                 2         2        /atan2(-12*im(a), -47 - 12*re(a))\     4 /                 2         2        /atan2(-12*im(a), -47 - 12*re(a))\
      \/  (-47 - 12*re(a))  + 144*im (a) *cos|--------------------------------|   I*\/  (-47 - 12*re(a))  + 144*im (a) *sin|--------------------------------|         \/  (-47 - 12*re(a))  + 144*im (a) *cos|--------------------------------|   I*\/  (-47 - 12*re(a))  + 144*im (a) *sin|--------------------------------|
  5                                          \               2                /                                            \               2                /     5                                          \               2                /                                            \               2                /
- - - ------------------------------------------------------------------------- - --------------------------------------------------------------------------- + - - + ------------------------------------------------------------------------- + ---------------------------------------------------------------------------
  2                                       2                                                                            2                                          2                                       2                                                                            2                                     
$$\left(- \frac{i \sqrt[4]{\left(- 12 \operatorname{re}{\left(a\right)} - 47\right)^{2} + 144 \left(\operatorname{im}{\left(a\right)}\right)^{2}} \sin{\left(\frac{\operatorname{atan_{2}}{\left(- 12 \operatorname{im}{\left(a\right)},- 12 \operatorname{re}{\left(a\right)} - 47 \right)}}{2} \right)}}{2} - \frac{\sqrt[4]{\left(- 12 \operatorname{re}{\left(a\right)} - 47\right)^{2} + 144 \left(\operatorname{im}{\left(a\right)}\right)^{2}} \cos{\left(\frac{\operatorname{atan_{2}}{\left(- 12 \operatorname{im}{\left(a\right)},- 12 \operatorname{re}{\left(a\right)} - 47 \right)}}{2} \right)}}{2} - \frac{5}{2}\right) + \left(\frac{i \sqrt[4]{\left(- 12 \operatorname{re}{\left(a\right)} - 47\right)^{2} + 144 \left(\operatorname{im}{\left(a\right)}\right)^{2}} \sin{\left(\frac{\operatorname{atan_{2}}{\left(- 12 \operatorname{im}{\left(a\right)},- 12 \operatorname{re}{\left(a\right)} - 47 \right)}}{2} \right)}}{2} + \frac{\sqrt[4]{\left(- 12 \operatorname{re}{\left(a\right)} - 47\right)^{2} + 144 \left(\operatorname{im}{\left(a\right)}\right)^{2}} \cos{\left(\frac{\operatorname{atan_{2}}{\left(- 12 \operatorname{im}{\left(a\right)},- 12 \operatorname{re}{\left(a\right)} - 47 \right)}}{2} \right)}}{2} - \frac{5}{2}\right)$$
=
-5
$$-5$$
producto
/         ________________________________                                              ________________________________                                      \ /         ________________________________                                              ________________________________                                      \
|      4 /                 2         2        /atan2(-12*im(a), -47 - 12*re(a))\     4 /                 2         2        /atan2(-12*im(a), -47 - 12*re(a))\| |      4 /                 2         2        /atan2(-12*im(a), -47 - 12*re(a))\     4 /                 2         2        /atan2(-12*im(a), -47 - 12*re(a))\|
|      \/  (-47 - 12*re(a))  + 144*im (a) *cos|--------------------------------|   I*\/  (-47 - 12*re(a))  + 144*im (a) *sin|--------------------------------|| |      \/  (-47 - 12*re(a))  + 144*im (a) *cos|--------------------------------|   I*\/  (-47 - 12*re(a))  + 144*im (a) *sin|--------------------------------||
|  5                                          \               2                /                                            \               2                /| |  5                                          \               2                /                                            \               2                /|
|- - - ------------------------------------------------------------------------- - ---------------------------------------------------------------------------|*|- - + ------------------------------------------------------------------------- + ---------------------------------------------------------------------------|
\  2                                       2                                                                            2                                     / \  2                                       2                                                                            2                                     /
$$\left(- \frac{i \sqrt[4]{\left(- 12 \operatorname{re}{\left(a\right)} - 47\right)^{2} + 144 \left(\operatorname{im}{\left(a\right)}\right)^{2}} \sin{\left(\frac{\operatorname{atan_{2}}{\left(- 12 \operatorname{im}{\left(a\right)},- 12 \operatorname{re}{\left(a\right)} - 47 \right)}}{2} \right)}}{2} - \frac{\sqrt[4]{\left(- 12 \operatorname{re}{\left(a\right)} - 47\right)^{2} + 144 \left(\operatorname{im}{\left(a\right)}\right)^{2}} \cos{\left(\frac{\operatorname{atan_{2}}{\left(- 12 \operatorname{im}{\left(a\right)},- 12 \operatorname{re}{\left(a\right)} - 47 \right)}}{2} \right)}}{2} - \frac{5}{2}\right) \left(\frac{i \sqrt[4]{\left(- 12 \operatorname{re}{\left(a\right)} - 47\right)^{2} + 144 \left(\operatorname{im}{\left(a\right)}\right)^{2}} \sin{\left(\frac{\operatorname{atan_{2}}{\left(- 12 \operatorname{im}{\left(a\right)},- 12 \operatorname{re}{\left(a\right)} - 47 \right)}}{2} \right)}}{2} + \frac{\sqrt[4]{\left(- 12 \operatorname{re}{\left(a\right)} - 47\right)^{2} + 144 \left(\operatorname{im}{\left(a\right)}\right)^{2}} \cos{\left(\frac{\operatorname{atan_{2}}{\left(- 12 \operatorname{im}{\left(a\right)},- 12 \operatorname{re}{\left(a\right)} - 47 \right)}}{2} \right)}}{2} - \frac{5}{2}\right)$$
=
18 + 3*re(a) + 3*I*im(a)
$$3 \operatorname{re}{\left(a\right)} + 3 i \operatorname{im}{\left(a\right)} + 18$$
18 + 3*re(a) + 3*i*im(a)