If an object is propelled upward from a height of s feet at an initial velocity of v feet per second, then its height h after t seconds is given by the equation h = -16t^2+vt+s, where h is in feet. if the object is propelled from a height of 12 feet with an initial velocity of 64 feet per second, it's height h is given by the equation h = -16t^2+64t+12. after how many seconds is the height 72 feet?

The object first reaches 72 feet after 1.5 seconds; it is this height again after 2.5 seconds.

Step-by-step explanation:

To find the amount of time it takes to reach 72 feet, we solve the equation

72 = -16t² + 64t + 12

To solve this, we will set it equal to 0 by subtracting 72 from each side:

72-72 = -16t² + 64t + 12 - 72

0 = -16t² + 64t - 60

Next we will use the quadratic formula to solve this:

answer: options?

step-by-step explanation:

introduction, methodology, results, discussion

step-by-step explanation:

an observational study is one which consists of actual observation to record data and then analyse the data.

there are a number of factors that should be analyzed before starting an observational study.

the main four factors are:

i) introduction:   this should be analysed to check whether the purpose of the study is correctly established and the data recorded are appropriate for the study

methodology:   the method of collecting the data, such as whether randomly selected, and whether sample size matches with the population to be studied, whether questions asked are easy to answer by common men, etc.

results: then results such as summary of data with comments should be studied thoroughly

discussion:   the last is the discussion, this can be either by management people or persons who are all interested , etc.