[br][math]F\left(x\right)=ax^2+bx+c[/math][br][math]F\left(0\right)=10\Longrightarrow c=10\Longrightarrow[/math][math]F\left(x\right)=ax^2+bx+10[/math][br][math]x_v=\frac{-b}{2a}\Longrightarrow\frac{-b}{2a}=\frac{1}{2}\Longrightarrow-b=a,b=-a;[/math][br][size=85]Let a=-1,b=1[br][math]F\left(x\right)=-x^2+x+10[/math][/size][br][math]x_v=\frac{-1}{2\left(-1\right)}=\frac{1}{2}[/math][br][math]y_v=F\left(\frac{1}{2}\right)\Longrightarrow-\frac{1}{4}+\frac{1}{2}+10=10,25\Longrightarrow[/math][math]V\left(\frac{1}{2},10,25\right)[/math]