Use the quadratic formula, given by:
[tex]x=\frac{-b\pm\sqrt[]{b^{2}-4ac}}{2a}[/tex]
where a, b and c are the coefficients of the equation:
ax² + bx + c = 0
By comparing the given equation 4x² + x - 9 = 0, with the previous general form, you have:
a = 4
b = 1
c = -9
replace the previous values of the parameters into the quadratic formula:
[tex]\begin{gathered} x=\frac{-1\pm\sqrt[\square]{(1)^{2}-4(4)(-9)}}{2(4)} \\ x=\frac{-1\pm\sqrt[]{145}}{8} \end{gathered}[/tex]
The previous expression contains the solutions to the given quadratic equation.
