Question

please solve this question

Answer 1

Sum of n terms =(4-1/n)+(4-2/n)+(4-3/n)+........+(4-n/n)
=(4n-1)/n+(4n-2)/n+(4n-3)/n.......(4n-n)/n

$\frac{4n - 1 + 4n -2 + 4n - 3 +.......... + 4n - n }{n}$
= [4n²-(1+2+3+......+n)]/n
= [4n²-{n*(n+1)}/2]/n
=[8n²-(n²+n)]/2n
=(8n²-n²-n)/2n
=(7n²-n)/2n
=[(7n-1)n]/2n
=(7n-1)/2 (answer)