Question
The height of a ball thrown into the air is a quadratic function of time, the ball is thrown from a height of 6 ft above the ground. After 1 second, the ball reaches its maximum height of 22 ft above the ground, write the equation of the function in vertex form.
Hint:
A quadratic function is one of the form f(x) = ax2 + bx + c, where a, b, and c are numbers with a not equal to zero.
The correct answer is: Hence, the equation of the function in vertex form is -16(t-1)2 + 22.
Let’s say that the quadratic equation representing the height of a ball thrown into the air as a function of time is h = at2 + bt + c
At t = 0, h = 6 ft
6 = 0 + 0 + c
c = 6
At t = 1 second, h = 22 ft
22 = a(1)2 + b(1) + 6
a + b = 16 …..(1)
Now, after 2 seconds, the ball will reach the height from which it is thrown i.e. 6 ft
At t = 2 seconds, h = 6 ft
6 = a(2)2 + b(2) + 6
4a + 2b = 0
b = -2a (2)
From equations 1 and 2
a + (-2a) = 16
a = -16
and b = 32
So, the quadratic equation is h = -16t2 + 32t + 6 = -16(t-1)2 + 22
Final Answer:
Hence, the equation of the function in vertex form is -16(t-1)2 + 22.
a + b = 16 …..(1)
Now, after 2 seconds, the ball will reach the height from which it is thrown i.e. 6 ft
From equations 1 and 2
a + (-2a) = 16
a = -16
and b = 32
So, the quadratic equation is h = -16t2 + 32t + 6 = -16(t-1)2 + 22
Final Answer:
Hence, the equation of the function in vertex form is -16(t-1)2 + 22.