a)
[tex]-3x^2+8x-11=0\\a=-3 => a<0 \text{ - ramiona paraboli skierowane w dol}\\b = 8\\c=-11\\\Delta=b^2-4ac\\\Delta=8^2-4*(-3)*(-11)\\\Delta=64-132=-68\\\text{brak rozwiazan}[/tex]
b)
[tex]-4x^2+3x-\frac9{16}=0\\a=-4 => a<0 \text{ - ramiona paraboli skierowane w dol}\\b=3\\c=-\frac9{16}\\\Delta=b^2-4ac\\\Delta=3^2-4*(-4)*(-\frac9{16})=9+16*(-\frac9{16})=9-9=0\\x_0=\frac{-b}{2a}\\x_0=\frac{-3}{2*(-4)}=\frac{-3}{-8}=\frac38[/tex]
