U4=7 U11=21 U34=.....?

Semoga ini jadi jawaban terbaik
Selamat belajar, jgn lupa follow

Un= a+b(n-1)
U4= a + b(4-1) =7
= a+3b = 7
U11= a+ b(11-1) =21
= a+ 10b=21

eliminasi a:

a+10b=21
a+3b=7
_________-
7b=14
b=2

a+3b=7
a+3(2)=7
a=7-6
a= 1

U34= a+b (n-1)
= 1+ 2(33)
= 1+ 66
= 67