Alvin throws the football to a receiver who jumps up to catch the ball. The height of the ball over time can be represented by the quadratic equation -4.9t2 + 7.5t + 1.8 = 2.1 . This equation is based on the acceleration of gravity -4.9 m/s2, the velocity of his pass is 7.5 m/s and releases the football at a height of 1.8 meters, and the height where the receiver catches the ball of 2.1 meters. Put the equation in standard form and then solve by using the quadratic equation.
-4.9t2 + 7.5t + 1.8 = 2.1 gives a specific time solution, not the height
of the ball over time ... anyway:
-4.9t2 + 7.5t + 1.8 = 2.1
4.9t^2 - 7.5t +.3 = 0 or
49t^2 - 75t + 3 = 0
for ax^2 + bx + c = 0,
x = (-b ± √(b^2 - 4ac) )/(2a)
you have the values of a, b, and c
plug them in and evaluate. Use only the positive value of t