just translate and use your definitions of an AS
a+3d = a+4d - 3
d = 3, hey, we got the common difference already
a+6d = 3(a+4d)
a + 6d = 3a + 12d
-2a = 6d = 18
a = -9
check:
terms are:
-9 -6 -3 0 3 6 9 12 15 ....
all conditions check out.
The fourth term of an arithmetic sequence is less than the fifth term by 3. The seventh term is three times the fifth term. Find the common difference and the first term
2 answers
20