Tuliskan lima suku pertama barisan Un=1/2n2+2n+5

Un = 1/2 n2 + 2n + 5

U1 = 1/2 1^2 + 2.1 + 5
U1 = 1/2 + 7
U1 = 1/2 + 14/2 = 15/2

U2 = 1/2 2^2 + 2.2 + 5
U2 = 4/2 + 4 + 5
U2 = 2 + 7 = 9

U3 = 1/2 3^3 + 2.3 + 5
U3 = 9/2 + 6 + 5
U3 = 9/2 + 12/2 + 10/2 = 31/2

U4 = 1/2 4^2 + 2.4 + 5
U4 = 16/2 + 8 + 5
U4 = 8 + 13 = 21

U5 = 1/2 5^2 + 2.5 + 5
U5 = 25/2 + 10 + 15
U5 = 25/2 + 20/2 + 30/2 = 75/2

Lima suku pertama yaitu
15/2, 9, 31/2, 21, 75/2

Semoga membantu ^-^