Question

Please help me with this problem. Which two equations would be most appropriately solved by using the quadratic formula?Select each correct answer.(x+8)(x+9)=0(x−3)^2=365x^2+7x=150.25x^2+0.8x−8=0

Answer 1

The first equation is already factorized, then, the roots are the zeros of each factor.

$(x+8)(x+9)=0\Rightarrow\begin{cases}x_1=-8 \\ x_2=-9\end{cases}$

The second equation can easily be solved by taking the square root on both sides.

$\begin{gathered} (x-3)^2=36 \\ \sqrt[]{(x-3)^2}=\pm\sqrt[]{36} \\ x-3=\pm6 \\ \begin{cases}x_1=9 \\ x_2=-3\end{cases} \end{gathered}$

The last two equations that need to be solve through the quadratic equation.