[tex]4x^2-9x-9=0\\\\a=4;\ b=-9;\ c=-9\\\\\Delta=b^2-4ac\to\Delta=(-9)^2-4\cdot4\cdot(-9)=81+144=225\\\\x_1=\dfrac{-b-\sqrt{\Delta}}{2a};\ x_2=\dfrac{-b+\sqrt{\Delta}}{2a}\\\\\sqrt\Delta=\sqrt{225}=15\\\\x_1=\dfrac{-(-9)-15}{2\xsor4}=\dfrac{9-15}{8}=\dfrac{-6}{8}=-\dfrac{3}{4}\\\\x_2=\dfrac{-(-9)+15}{2\cdot4}=\dfrac{9+15}{8}=\dfrac{24}{8}=3[/tex]
[tex]Answer:\boxed{x=-\dfrac{3}{4}\ or\ x=3}[/tex]
