Question

Carilah banyak suku(n) dari setiap barisan aritmetika berikut!
a.7,13,19,25,...;Un=463
b.852,849,846,843,...;Un=0
c.2,17,32,47,...;Un=3.362
d.88,84,80,76,...;Un=-4
e.9,9 1/4, 9 1/2, 9 3/4, ...;Un=365

Answer 1

A. Un = U1 +(n-1)b => 7 + (n-1)6 => 7+6n-6
    463 = 6n+1 => 6n = 463-1 => 6n = 462 => n = 462:2 = 77

b. 0 = 852 +(n-1)-3 => 852 -3n+3 =>
    0 = 855 -3n => 3n = 855 => n = 855:3 => n=283

c.3362 = 2+(n-1)15 => 2+15n-15
   3362 = 15n -13 => 15n = 3362+13 => 15n = 3375 => n=225

d. -4=88+(n-1)-4 => 88 -4n +4 => 92-4n
    -4 = 92-4n => 4n = 92+4 => 4n=96 => n=24

e. 365= 9 +(n-1)1/4 => 9+1/4n-1/4 => 8 3/4 +1/4n
   365 = 8 3/4 +1/4n => 1/4n = 373 3/4 => n= 373 3/4 : 1/4 => n= 1495

Answer 2

A.((un - u1) : b) +1
   ((463-7): 6) +1
   77

b.283
c.225
d.24
e.1425