Question

Answer:

Step by step explanation:​

Answer 1

Explanation:

a)
`t_(n)` = 2n - 3

`t_(1)=2*1-3 = 2-3=-1\\\\t_(2)=2*2-3=4-3=1\\\\t_(3)=2*3-3=6-3=3\\\\t_(4)=2*4-3=8-3=5\\\\S_(4)=t_(1)+t_(2)+t_(3)+t_(4)\\\\= -1 + 1 + 3 + 5 \\\\= 8`

d)

`t_(n)=(2n-1)/(2n+1)\\\\\\t_(1)=(2-1)/(2+1)=(1)/(3)\\\\t_(2)=(4-1)/(4+1)=(3)/(5)\\\\t_(3)=(6-1)/(6+1)=(5)/(7)\\\\t_(4)=(8-1)/(8+1)=(7)/(9)\\\\`

`S_(n)=(n)/(2)(a+l)\\\\S_(4)=(4)/(2)((1)/(3)+(7)/(9))\\\\=2*((1*3)/(3*3)+(7)/(9))\\\\=2*((3)/(9)+(7)/(9))\\\\=2*(10)/(9)\\\\=(20)/(9)`