A football punted into the air is modeled by the quadratic function y = -16x^2 + 51x + 3 where x is the time in seconds and y is the height of the football in feet. As the football descends, at what time is it at a height of
12 feet?

4. a spring scale is constructed so that each 0.10-n increment is separated by 0.50 cm. what spring constant is necessary for the scale to be accurate? -1.0n/cm -0.10n/cm -9.8 n/cm -0.20n/cm

Which statements are true? check all that apply. the line x = 0 is perpendicular to the line y = –3. all lines that are parallel to the y-axis are vertical lines. all lines that are perpendicular to the x-axis have a slope of 0. the equation of the line parallel to the x-axis that passes through the point (2, –6) is x = 2. the equation of the line perpendicular to the y-axis that passes through the point (–5, 1) is y = 1.

Solve the following simultaneous equation by using an algebraic method (either substitution or elimination) 2x + 3y=-4 4x-y=11