KK bantu jawab soal matematika
Jawab:
1. 48
2. 2
3. 59
4. 125
5. r= -3
6. Un= 32 x 2^n
Penjelasan dengan langkah-langkah:
1.
a= 12
84=a+ (n-1)b
84= 12+ (n-1)b
72= (n-1)b
Suku tengah= a+ (n-1)b/2
= 12+72/2
= 12+36
= 48
2.
beda=(53-15)/(18+1)
= 38/19
= 2
3.
beda baru= (8-2)/(1+1)
= 6/2
= 3
maka menjadi:
2, 5, 8, 11, 14, 17, ....
maka a= 2, b=3
U20 = a+ 19b
= 2+19(3)
= 2 +57
= 59
4.
1, 6, 14, 25
5 8 11
3 3
2a= 3
a= 3/2
3a+b= 5
3(3/2)+b= 5
9/2+b= 5
b= 1/2
1= a+b+c
1= 3/2+1/2+c
1= 2+c
c= -1
Un= 3/2n^2+1/2n-1
U9= 3/2(9)^2+1/2(9)-1
= 3/2(81)+9/2-1
= 243/2+9/2-1
= 126-1
= 125
5.
r= U2/U1= U3/U2= Un/Un-1
r= -6/2
r= -3
6.
a= 64
r= 128/64= 2
Un= ar^(n-1)
= 64(2^(n-1))
= 64 x 1/2 x 2^n
= 32 x 2^n
