\(y=-0,4x^2+14x |:(-0,4)\)
\(\frac{y}{-0,4}+\red{(\frac{35}{2})^2}=x^2-35x+\red{(\frac{35}{2})^2} \)
\(\frac{y}{-0,4}+\red{(\frac{35}{2})^2}=(x-\red{(\frac{35}{2})} )^2 \)
\(\frac{y}{-0,4}+306,25=(x-17,5 )^2 |\cdot(-0,4)\)
\(y-122,5= -0,4\cdot(x-17,5 )^2 \)
\(y= -0,4\cdot(x-17,5 )^2 +122,5 \)
\(S(17,5|122,5)\)