Question

pliss bantuin ya kak

jangan ngasal2​

Answer 1

Jawaban:

==> Suku Ke 10 <==

U10 = a + ( n - 1 )b

= a + ( 10 - 1)b

= a + 9b

= 3 + 9(5)

= 3 + 45

= 48

==> Jadi U10 = 48 <==

Answer 2

U1 = 3

U2 = 8

U3 = 15

Un = an² + bn + c

U1 = a(1)² + b(1) + c

a + b + c = 3 ..... (1)

U2 = a(2)² + b(2) + c

4a + 2b + c = 8 ..... (2)

U3 = a(3)² + b(3) + c

9a + 3b + c = 15 ..... (3)

eliminasi (2) dengan (1) :

4a + 2b + c = 8

a + b + c = 3

____________-

3a + b = 5 ..... (4)

eliminasi (3) dengan (2) :

9a + 3b + c = 15

4a + 2b + c = 8

_____________-

5a + b = 7 ..... (5)

eliminasi (5) dengan (4) :

5a + b = 7

3a + b = 5

________-

2a = 2

a = 1

substitusi a ke 4

3a + b = 5

3(1) + b = 5

b = 5 -3

b = 2

substitusi a dan b ke (1)

a + b + c = 3

1 + 2 + c = 3

c = 0

Un = an² + bn + c

Un = n² + 2n

U10 = 10² + 2(10)

U10 = 100 + 20

U10 = 120