SOLUTION: The first term of an arithmetic progression is -8.The ratio of the 7th term to the 9th is 5:8. Calculate the common difference

Question 1132681: The first term of an arithmetic progression is -8.The ratio of the 7th term to the 9th is 5:8. Calculate the common difference
Found 2 solutions by MathLover1, MathTherapy:
Answer by MathLover1(20850) (Show Source): You can put this solution on YOUR website!
an arithmetic progression is:
, , , ,.........and so on.
Thus nth term of an AP series is
, where term and = first term. and is common difference =

given:

since and , we have

, , , ,,, , ,
so, your sequence is:
,, , , , , , ,
chech the ratio of the 7th term to the 9th if it is

-> confirmed

Answer by MathTherapy(10552) (Show Source): You can put this solution on YOUR website!

The first term of an arithmetic progression is -8.The ratio of the 7th term to the 9th is 5:8. Calculate the common difference

We then get:
8(- 8 + 6d) = 5(- 8 + 8d) ------- Cross-multiplying
- 64 + 48d = - 40 + 40d
48d - 40d = - 40 + 64
8d = 24
d, or common difference =
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