Tentukan unsur-unsur yg dinyatakan pada barisan aritmatika ini! A. a=8,b=5, u101= B. a=3, u15=143,b= C. b=15,u21=295,a= D. a=12,b=-2,un=-122, n= E. u5=3,u12=-18

a. U101
= a + 100b
= 8 + 100(5)
= 8 + 500
= 508

b. U15 = a + 14b
143 = 3 + 14b
143 - 3 = 14b
140 = 14b
b = 140/14
b = 10

c. U21 = a + 20b
295 = a + 20(15)
295 = a + 300
a = 300 - 295
a = 5

d. Un = a + (n-1)b
-122 = 12 + (n-1)(-2)
-122 - 12 = -2n + 2
-134 - 2 = -2n
-136 = -2n
n = -136/-2
n = 68

e.
U5 = a + 4b
3 = a + 4b
3 - 4b = a

U12 = a + 11b
-18 = 3 - 4b + 11b
-18 - 3 = 7b
-21 = 7b
b = -21/7
b = -3

a = 3 - 4b
a = 3 - 4(-3)
a = 3 + 12
a = 15

f.
U4 = a + 3b
4 = a + 3b
4 - 3b = a

U8 - U3 = 15
a + 7b - ( a + 2b ) = 15
5b = 15
b = 15/5
b = 3

a = 4 - 3b
a = 4 - 3(3)
a = 4 - 9
a = -5



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