if the 8th term of an A.P is twice the 5th term, find the 12th term
2 answers
What subject is "francis"?
the 8th term of an A.P is twice the 5th term
----> a + 7d = 2(a+4d)
a+7d = 2a + 8d
a = -d
12th term = a + 11d
= -d + 11d
= 10d
e.g. let d = 4, then a = -4
term(8) = -4 + 7(4) = 24
term(5) = -4 + 4(4) = 12
so term 8 is twice term 5
term 12 = -4+11(4) = 40 which is 10d or 10(4)
As you can see there is so unique answer to your problem, just let d equal anything you want, as long as "a" is its opposite, it will work
----> a + 7d = 2(a+4d)
a+7d = 2a + 8d
a = -d
12th term = a + 11d
= -d + 11d
= 10d
e.g. let d = 4, then a = -4
term(8) = -4 + 7(4) = 24
term(5) = -4 + 4(4) = 12
so term 8 is twice term 5
term 12 = -4+11(4) = 40 which is 10d or 10(4)
As you can see there is so unique answer to your problem, just let d equal anything you want, as long as "a" is its opposite, it will work