Tolong Jawab Dengan Caranya​

Jawaban:

Deret dan Barisan Bilangan Aritmatika

Penjelasan dengan langkah-langkah:

1. 4 7 10 13

a=4

b=3

Un=a+(n-1)b

=4+(n-1)3

=4+3n-3

=3n+1

U₂₀=3(20)+1

=60+1

=61

Sn=n/2(a+Un)

S₂₀=20/2(4+U₂₀)

=10(4+61)

=10(65)

=650

2. 1 + 3 + 5 + 7 + 9 + …. + 111 =

a=1

b=2

Un=a+(n-1)b

=1+(n-1)2

=1+2n-2

=2n-1

Un=2n-1

111=2n-1

111+1=2n

112=2n

n=112/2

n=56

S₅₆=n/2(a+Un)

=56/2(1+U₅₆)

=28(1+111)

=28(112)

=3.136

3. 1 3 5 7 9 11

a=1

b=2

Un=a+(n-1)b

=1+(n-1)2

=1+2n-2

=2n-1

U₁₃=2(13)-1

=26-1

=25

Sn=n/2(a+Un)

S₁₃=13/2(1+U₁₃)

=13/2(1+25)

=13/2(26)

=13×13

=169

4. 8 + 13 + 18 + 23 + ...

a=8

b=5

Un=a+(n-1)b

=8+(n-1)5

=8+5n-5

=5n+3

U₂₄=5(24)+3

=123

Sn=n/2(a+Un)

S₂₄=24/2(8+U₂₄)

=12(8+123)

=12(131)

=1.572

5. 5 9 13 ….

a=5

b=4

Un=a+(n-1)b

=5+(n-1)4

=5+4n-4

=4n+1

U₇=4(7)+1

=28+1

=29

Sn=n/2(a+Un)

S₇ =7/2(5+U₇)

=7/2(5+29)

=7/2(34)

=7×17

=119

Demikian

Semoga membantu dan bermanfaat!