Question

Determining the first three terms of an ArithmetiC progressionof which the (a.)10th term is 31 and the 15th term is 49 (b.)7th term is 3 and 12th term is -3 (c.)5th term is 8 and the 11th term is -28 (d.)9th term is7+9x and d=2x,Show all calculations
Steve
(a)
a+9d = 31
a+14d = 49
d = 18/5
a = -7/5
so, we have

-7/5, 11/5, 29/5, ...

(b) and (c) are just the same.

(d)
a+8d = a+16x = 7+9x
a = 7-7x

so,

7-7x, 7-5x, 7-3x ...