Answer:
(-3 ÷ 4)x^2 + 6x
Step-by-step explanation:
Data mentioned in the question
Maximum height = 12m
Number of seconds = 8
Height = 3m
Depend on the above information, the quadratic equation is shown below:
As it took 8 seconds to hit the maximum altitude and it reverted to the ground floor, this graph also reflects the motion in parabola after 4 seconds, so that the a must be negative
Now it is given that
a × x ^ 2 + bx + c =0
We can considered that
x = 0
x = 8
As {0.8} are intercepts of x
When x = 0, then it is
a × 0 ^ 2 + b(0) + c = 0 .................... (i)
Hence 0 = 0
Now x = 8, it is
a × 8 ^ 2 + b(8) + c = 0
Hence a(8)^2 + b(8) + c = 0 ..................(ii)
As it can be seen that in the first equation c must be zero
Whereas the second equation is
64a + 8b = 0
i.e.
8a = -b or a = -b ÷ 8
Now according to the quadratic function, it presented
(-b ÷8)x^2 + bx + 0
So, the parabola vertex is (4, 12)
Now place this in the place of a
(-b ÷ 8)(4)^2 + b(4) = 12
And for calculating this b, all terms must be multiplied by 8
That appears
-b(16) + 32b = 96
16b = 96
So, b = 6.
As a = -b ÷8
a = -6 ÷ 8
a = -3 ÷4
So, the equation is
= (-3 ÷ 4)x^2 + 6x
Hence, this is the equation
