Bantu kerjakan Nomor 10 Kakak mohon dengan caranya yah

dik=u4=5
u10=29
dit=u15=?
jwb=-)mencari b
b=u10-u4
————
10-4
=29-5
———
6
=24/6
b=4
-)mencari a
u4=a+(n-1)b
5=a+3x4
5=a+12
a=5-12
a=-7
-)mencari u15
u15=a+(n-1)b
=-7+14x4
=-7+56
u15=49

maaf kalau salah

Mapel Matematika
Bab Baris dan Deret

U4 = 5
a + 3b = 5

U10 = 29
a + 9b = 29
a + 3b + 6b = 29
5 + 6b = 29
6b = 24
b = 4

a + 3b = 5
a + 3(4) = 5
a = -7

Sn = n/2 (2a + (n - 1)b)
S15 = 15/2 (2(-7) + 14(4))
S15 = 15/2 (-14 + 56)
S15 = 15/2 (42)
S15 = 15(21)
S15 = 315