32,21,10,-1,...,tentukan suku ke - 15

Un=a+(n-1)b
U15=32+(15-1)*-11
U15=32+14*-11
U15=32+(-154)
U15=-122

32, 21, 10, -1...

Un = an + b

21 = 2a + b
32 = a + b —
----------------
-11 = a

32 = -11 + b
b = 32 + 11
b = 43

Rumus : Un = -11n + 43

U15 = -11.15 + 43
U15 = -165 + 43
U15 = -122

Maaf bila ada kesalahan