Question

3x ao quadrado -15x+12=0

Answer 1

$\Large\displaystyle\begin{gathered} \sf{3x^2-15x+12=0 } \end{gathered}$

$\Large\displaystyle\text{ \begin{gathered} \sf{ \begin{cases}\sf a=3\\\sf b=-15\\\sf c=12\end{cases}} \end{gathered} }$

$\Large\displaystyle\begin{gathered} \sf{ \Delta=b^2-4ac} \end{gathered}$

$\Large\displaystyle\begin{gathered} \sf{ \Delta=(-15)^2-4\cdot3\cdot12} \end{gathered}$

$\Large\displaystyle\begin{gathered} \sf{ \Delta=225-144} \end{gathered}$

$\Large\displaystyle\begin{gathered} \sf{\Delta=81 } \end{gathered}$

$\Large\displaystyle\text{ \begin{gathered} \sf{ x=\dfrac{-b\pm\sqrt{\Delta}}{2a}} \end{gathered} }$

$\Large\displaystyle\text{ \begin{gathered} \sf{ x=\dfrac{-(-15)\pm\sqrt{81}}{2\cdot3}} \end{gathered} }$

$\Large\displaystyle\text{ \begin{gathered} \sf{ x=\dfrac{15\pm9}{6}\begin{cases}\sf x_1=\dfrac{15+9}{6}=\dfrac{24}{6}=4\\\\\sf x_2=\dfrac{15-9}{6}=\dfrac{6}{6}=1\end{cases}} \end{gathered} }$