Find the nth term of this sequence 1 3 5 7 9

x+2, I believe. each number you're adding 2 to the previous number. 

We can use the formula Tn=pn+q

Okay so the difference between the terms is a constant two. this means that p in your formula = 2
because -1+2=1... 1+2=3... 3+2=5
so far you have Tn=(2)n+q
now use the method of substitution to find q. use the 1st term. T1 = 1
so
Tn=2n+q
1=2(1)+q                          [2 x 1 = 2]
1=2+q                              
1-2=q                               [variables one side ; numbers on the other side]
q = -1

so your general term is
Tn=2n-1

Set up a system of equations