An explicit formula is used to find any term in a sequence by putting in the number of that term in place of the unknown variable.
In order to find the first four terms, we need to plug values, from 1-4, separately in each of the formulas.
For f(n) = 7(n+1) - 11, put values from 1-4 in place of n:
f(1) = 7(1+1) - 11 = 3 ----> First term
f(2) = 7(2+1) - 11 = 10 ----> Second term
f(3) = 7(3+1) - 11 = 17 ----> Third term
f(4) = 7(4+1) - 11 = 24 ----> Fourth term
For f(n) = 65 - 10n, put values from 1-4 in place of n:
f(1) = 65 - 10(1) = 55 ----> First term
f(2) = 65 - 10(2) = 45 ----> Second term
f(3) = 65 - 10(3) = 35 ----> Third term
f(4) = 65 - 10(4) = 25 ----> Fourth term