Question

 x²-3x-40 ? PS:sou péssima em equação do 2º grau 

Answer 1

$x^{2} -3x-40=0\\ \\ \Delta=(-3)^2-4.1.(-40)=9+160=169\\ \\ x=\frac{-b \pm \sqrt {\Delta}}{2a}\\ \\ x=\frac{3 \pm \sqrt{169}}{2}=\frac{3 \pm 13}{2}\\ \\ x_1=\frac{3-13}{2}=-5\\ \\ x_2=\frac{3+13}{2}=6$

Answer 2

x''-3x-40=
x''+3x-40
x''-40+3x
39x''+3x''
x=42x''