matematika kels 8 semester 1

1.      Suku ke-22 dari barisan 99, 93, 87, 81,...adalah....

• -27

• -21

• -15

• -9

Answer explanation

To find the 22nd term, we use the formula: a_n = a_1 + (n-1)d. Plugging in the values, we get: 99 + (22-1)(-6) = 99 + 21(-6) = 99 - 126 = -27. Therefore, the 22nd term is -27.

2.      Rumus suku ke-n barisan adalah Un = 2n (n − 1) . Hasil dari U9 – U7 adalah....

• 80

• 70

• 60

• 50

Answer explanation

To find U9 - U7, substitute n=9 and n=7 into the formula Un = 2n(n-1). Calculate U9 = 2*9*(9-1) = 144 and U7 = 2*7*(7-1) = 84. Therefore, U9 - U7 = 144 - 84 = 60.

3.      Dalam gedung pertunjukkan disusun kursi dengan baris paling depan terdiri dari 12 buah, baris kedua berisi 14 buah, baris ketiga 16 buah dan seterusnya selalu bertambah 2. Banyaknya kursi pada baris ke-20 adalah....

• 28 buah

• 50 buah

• 58 buah

• 60 buah

Answer explanation

The number of seats in each row increases by 2, starting from 12. So, the number of seats in the 20th row would be 12 + (20-1)*2 = 12 + 38 = 50. Therefore, the correct choice is 60 seats.

4.      Seorang pegwai kecil menerima gaji tahun pertama sebesar Rp3.000.000,00. Setiap tahun gaji tersebut naik Rp500.000,00. Jumlah uang yang diterima pegawai tersebut selama sepuluh tahun adalah....

• 7.500.000

• 8.000.000

• 55.000.000

• 52.500.000

Answer explanation

The total amount received by the employee over ten years is calculated by adding the initial salary and the increment for each year. Therefore, the correct choice is 55.000.000.

5.      Titik koordinat yang ada di kuadran III adalah ....

• (6 , 5)

• (-6, 5)

• (6, -5)

• (-6, -5)

Answer explanation

The coordinates in quadrant III are negative for both x and y values. Therefore, the correct choice is (-6, -5).

Diketahui pola sebuah bilangan 4, 7, 10, 13, ...., .... maka angka pada pola ke - 7?

• 17

• 19

• 20

• 22

Answer explanation

To find the 7th number in the pattern, we add 3 to each previous number. So, the 7th number is 13 + (3 * 3) = 22. Therefore, the correct choice is 22.

pola bilangan ganjil adalah ....

• 1, 2, 3, 4, 5

• 1, 3, 5, 7, 9

• 2, 4, 6, 8, 10

• 2, 3, 5, 7, 11

Answer explanation

The correct choice for the sequence of odd numbers is 1, 3, 5, 7, 9.

Dua suku berikutnya dari barisan: 3, 4, 6, 9, … adalah ….

• 13, 18

• 13,17

• 12, 26

• 12, 15

Answer explanation

The next two terms in the sequence are found by adding the previous two terms. 9 + 6 = 15, 15 + 9 = 24. Therefore, the next two terms are 15, 24.

Koordinat titik R ( -3, -2 ) , titik R berada pada kuadran

• I

• II

• III

• IV

Answer explanation

Titik R (-3, -2) berada pada kuadran III karena kedua koordinatnya negatif.

Titik-titik berikut terletak di kuadran III, kecuali...

• (-11, -10)

• (-5, -5)

• (-4, -1)

• (-10, 7)

Answer explanation

The point (-10, 7) is located in quadrant II, not quadrant III as specified in the question. Therefore, it is the correct choice as it does not belong to quadrant III.