Eg4 please...Why are 'means' taken as a-d,a+d and not the other two?

Asked by drhimasingh | 25th Dec, 2019, 08:30: PM

Expert Answer:

Extremes are the numbers at the end which are (a-3d) and (a+3d)
(a-d) and (a+d) are the means because in an AP a,b,c,d
b is the mean of a and c
c is the mean of b and d
Hence, (a-d) and (a+d) are taken as means. 

Answered by Renu Varma | 26th Dec, 2019, 10:53: AM