Answer:
1) xₙ = n² - (n - 1)
2) 1/4
Step-by-step explanation:
1) 1 = 1² - (1-1)
3 = 2² - (2-1)
7 = 3² - (3-1)
13 = 4² - (4-1)
...........
xₙ = n² - (n - 1)
2) three consecutive terms of an exponential sequence: x, rx , r²x
x: 2nd term of linear sequence
rx: 6th term of linear sequence rx = x + 4d
r²x: 7th term of linear sequence r²x = rx + d d = r²x - rx
rx = x + 4 * (r²x - rx) = x + 4r²x - 4rx
4xr² -5rx + x = 0
x(4r² -5r + 1) = 0
x (4r - 1) ( r - 1) = 0
x = 0 or r = 1/4 or r = 1
if either x = 0 or r = 1 d will be equals to "0" everything became 0
So the only reasonable answer is r = 1/4
