Use the formula -b/2a and -D/4a only please and answer as soon as possible

Hello friend.. You know that its greatest value would be when its denominator is minimum. For the quadratic 4x²+2x+1 its minimum value would be at -b/2a which is -1/4. And it`s minimum value is -D/4a which is 12/16 or 3/4.. Hence the original function has maximum value as 4/3..