Question

Jumlah deret berikut 3 + 7 + 11 + 15 + ..... +71 adalahh
pake cara ..

Answer 1

Suku pertama (a) = 3
beda (b) = 4
banyaknya suku :
Un = 3+(n-1)4
71 = 3+4n-4
3+4n-4 = 71
4n = 71-3+4
4n = 72
n = 72/4 = 18

Jumlah deret :
Sn = n/2 (2a + (n-1)b)
S18 = 18/2 (2x3 + (17)4)
       = 9 (6 + 68)
       = 666

Answer 2

A / u1= 3, b= 4, Un = 71, u2 = 7 Un = a + (n-1) b 7 = a +b 3 = a. (Kmudian dieliminasi) 4 = b Un = a + (n-1) b 7 = a+b 7 = a+4 3 = a Un= a+(n-1) b 71 = 3 + (n-1) 4 71= 3 + 4n -4 72 = 4n 18 = n Sn = 1/2 n (2a+(n-1)b) S18 = 9 (2.3+17.4) = 9 (6+68) = 9. 74 = 666 Jadi jumlah deret adlh 666 Smoga membantu^^