Tentukan nilai x,jika (2x+1) + (2x+2) +(2x+3) + ….. + (2x +50)= 4275
Jawaban Terkonfirmasi
(2x+1)+(2x+2)+(2x+3)+ … + (2x+50) = 4275
beda = (2x+2)-(2x+1)
= 2x+2-2x-1
= 1
Un = U1 + (n-1)b
2x+50 = (2x+1) + (n-1)1
2x+50 = 2x+1 + n – 1
2x-2x = n – 1 + 1 – 50
50 = n
Sn = n/2
. (U1+Un)
4275 = 50/2 . ((2x+1)+(2x+50))
4275 = 25 . (4x+51)
171 = 4x+51
120 = 4x
30 = x