jawab no 3 yg b sama c nya aja pake cara cptan ya besok dikumpulin

Mapel : Matematika
Kelas : VIII SMP
Bab : Pola Bilangan

Pembahasan :
Un = 2n - 1
99 = 2n - 1
2n = 100
n = 50

1 + 3 + 5 + ... + 99 = n²
1 + 3 + 5 + ... + 99 = 50²
1 + 3 + 5 + ... + 99 = 2500

————————————————
1 - 2 + 3 - 4 + ... - 100
= -1 - 1 - 1 - ... - 1
= - (1 + 1 + 1 + ...)
= -(100/2)
= -50

————————————————
Un = 50
a + (n - 1)b = 50
-100 + (n - 1)1 = 50
n - 101 = 50
n = 151

-100 - 99 - 98 - ... + 50
= S151
= 151/2(-100 + 50)
= 151/2(-50)
= -3775 ——» Hasil akhir