mohon di jawab berikan penjelasan dan penjabaran , terima kasih

cuma bisa nomor 8 doang

7) (x - 1), (2x + 2), (7x + 1), ..., 72
U2 - U1 = U3 - U2
(2x + 2) - (x - 1) = (7x + 1) - (2x + 2)
x + 3 = 5x - 1
-4x = -4
x = 1
(x - 1), (2x + 2), (7x + 1), ... , 72
0, 4, 8, ..., 72 => b = 8
Karena yang ditanya suku kelima terakhir maka
a = 72 dan b = -4
U5 = a + 4b = 72 + 4(-4) = 72 - 16 = 57

8) A (1) = 2 (1) ==> A (1) = (2)
.........(2) .... (2) ......... (2) .. (4)

A (1) = 3 (1) ==> A (1) = (3)
... (1) ...... (1) ........... (1) .. (3)

A (1 ... 1) = (2 ... 3)
... (2 .. 1) .. (4 ... 3)

|A| (1.1 - 2.1) = (2.3 - 4.3)
|A| (-1) = -6
|A| = -6/-1 = 6

9) 5 pasang suami istri duduk = 10 orang => n(S) = 10!
Pak Tri dan Istrinya duduk bersebelahan (2 orang dianggap 1) => 2!
n = 8 + 1 = 9 => 9! ==> n(A) = 9!.2!
Peluang = n(A)/n(S) = (9!.2!)/10! = (9!.2)/(10.9!) = 2/10 = 1/5

10) xy + 2√y = 5
..... xy - √y = a =====> xy = a + √y ==> x = (a + √y)/y
------------------- --
3√y = (5 - a)
√y = (5 - a)/3
Karena a ≤ 10 => a bilangan asli positif
a = 1 => √y = (5 - 1)/3 = 4/3 => y = 16/9
x = (1 + 4/3)/(16/9) = (7/3)/(16/9) = 21/16 bukan bil bulat

a = 2 => √y = (5 - 2)/3 = 1 => y = 1
x = (2 + 1)/1 = 3

a = 3 => √y = (5 - 3)/3 = 2/3 => y = 4/9
x = (3 + 2/3)/(4/9) = (11/3)/(4/9) = 33/4 bukan bilangan bulat

a = 4 => √y = (5 - 4)/3 = 1/3 => y = 1/9
x = (4 + 1/3)/(1/9) = (13/3)/(1/9) = 39

a = 5 => √y = (5 - 5)/3 = 0 => y = 0
x = (5 + 0)/0 = ~

Untuk a = 6,7,8,9,10 diperoleh √y = negatif

Jadi banyaknya bilangan bulat x ada 2 yaitu 1 dan 39