Hitunglah jumlah 8 suku pertama deret bilangan berikut.

A.S8= n/2(2a+(n-1))b
= 8/2(2(-2)+(8-1))4
=4(-4+(7))4
=4(-4+28)
=4(24)
=96
b.S8= n/2(2a+(n-1))b
= 8/2(2.12+(8-1))8
= 4(24+(7))8
= 4(24+56)
=4.80
= 320

A.-20
b.96

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