The Total solution for NCERT class 6-12
Given:
Sum of GP =┬а381
Where, a = 3, r = 6/3= 2, n = ?
By using the formula,
Sum of GP for n terms= a(rn┬атАУ 1 )/(r тАУ 1)
381 = 3 (2n┬атАУ1)/ (2-1)
381 = 3 (2n┬атАУ1)
381/3 = 2n┬атАУ1
127 = 2n┬атАУ1
127 + 1 = 2n
128 = 2n
27┬а= 2n
n = 7
тИ┤ value of n is 7