Quadratic formula
[tex]x=\frac{-b\pm\sqrt[]{b^2-4ac}}{2a}[/tex]Where a is the coefficient of the first term, b the coefficient of the second term and c the coefficient of third term
a)
[tex]3x^2-7x+4=0[/tex]replacing on the quadratic formula
[tex]x=\frac{-(-7)\pm\sqrt[]{(-7)^2-4(3)(4)}}{2(3)}[/tex]simplify
[tex]\begin{gathered} x=\frac{7\pm\sqrt[]{49-48}}{6} \\ \\ x=\frac{7\pm\sqrt[]{1}}{6} \\ \\ x=\frac{7\pm1}{6} \end{gathered}[/tex]x has two solutions
[tex]\begin{gathered} x_1=\frac{7+1}{6}=\frac{4}{3} \\ \\ x_2=\frac{7-1}{6}=1 \end{gathered}[/tex]b)
[tex]5x^2+3x=9[/tex]rewrite on general form
[tex]5x^2+3x-9=0[/tex]raplace on quadratic formula
[tex]x=\frac{-(3)\pm\sqrt[]{(3)^2-4(5)(-9)}}{2(5)}[/tex]simplify
[tex]\begin{gathered} x=\frac{-3\pm\sqrt[]{9+180}}{10} \\ \\ x=\frac{-3\pm\sqrt[]{189}}{10} \end{gathered}[/tex]x has two solutions
[tex]\begin{gathered} x_1=\frac{-3+\sqrt[]{189}}{10}\approx1.075 \\ \\ x_2=\frac{-3-\sqrt[]{189}}{10}\approx-1.67 \end{gathered}[/tex]