Question

100,95,90,85
tentukan u25 dan s5 deret aritmatika
ada yang tau cara ngitungnya?

Answer 1

A = 100
b = 95-100 = -5
Un = a + (n-1)b
U25 = 100+(25-1)(-5)
U25 = 100+(-120)
U25 = 100-120
U25 = -20
Sn = n/2 (2a+(n-1)b)
S5 = 5/2 {2(100)+(5-1)(-5)}
S5 = 5/2 {200 + 4(-5)}
S5 = 5/2 (200 - 20)
S5 = 5/2 (180)
S5 = 5(90)
S5 = 450
semoga dapat di pahami

Answer 2

100,95,90,85 U25 = a + (n-1)b . = 100 + (25-1) (-5) = 100 + 24. (-5) = 100 - 120 = -20 S5 = n/2 (100+ (n-1) b) =5/2 (100 + 24 (-5) ) = 5/2 (100-20) =5/2 . 80 =5 x 40 =200