jawaban dari soal trsbt adalah

Mapel : Matematika
Bab : Barisan dan deret

U3 = 7 = a + 2b
U7 = 15 = a + 6b
_____________ _
-8 = -4b
b = -8/-4
b = 2

a + 2b = 7
a + 2(2) = 7
a + 4 = 7
a = 7 - 4
a = 3

S30 = 30/2(2(3) + (30 - 1) 2)
S30 = 15(6 + 29 × 2)
S30 = 15(6 + 58)
S30 = 15(64)
S30 = 960

(A)

diketahui U3 = 7 => a + 2b =7
U7 = 15 => a +6b =15

eliminasi

a+2b =7
a+6b = 15
________ -

-4b = -8
b = 2

subtitusi

a+2b=7
a+2 (2) =7
a+4 = 7
a = 3

S30 = n/2 (2a+n-1. b)
= 30/2 (2 (3)+30-1 (2))
= 15 (6+58)
=15 (64)
=960
jawaban A