The work of a student to solve a set of equations is shown:
equation a: y = 4 − 2z
equation b: 4y = 2 − 4z
step 1:
−4(y) = −4(4 − 2z) [equation a is multiplied by −4.]
4y = 2 − 4z [equation b]
step 2:
−4y = 4 − 2z [equation a in step 1 is simplified.]
4y = 2 − 4z [equation b]
step 3:
0 = 6 − 6z [equations in step 2 are added.]
step 4:
6z = 6
step 5:
z = 1
in which step did the student first make an error?
step 1
step 3
step 4
step 2

If you would like to know in which step did the student first make an error, you can find this using the following steps:

y = 4 - 2z
4y = 2 - 4z

-4(y) = -4(4 - 2z)
4y = 2 - 4z

-4y = -16 + 8z ... Step 2
4y = 2 - 4z

0 = -16 + 8z + 2 - 4z

16 - 2 = 4z

14 = 4z

z = 14/4 = 7/2

The correct result would be: Student made an error in Step 2.

47

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.