a + 3 d = 15
a + 6 d = 27
----------------- subtract
-3 d = - 12
d = 4
onward and upward
THE 4th and 7th term of a.p are 15 and 27 respectively.find (a)the 1st term (b) common difference
4 answers
The 4th and 7th term of a.p are 15 and 27 respectively. Find (a) the 1st term (b) common difference
Ah, I just told you how to do it.
In an Arithmetic Progression:
an = a1 + ( n - 1 ) d
where
a1 = the initial term
d = the common difference of successive members is d,
an = the nth term
In this case:
a4 = a1 + ( 4 - 1 ) d = 15
a1 + 3 d = 15
a7 = a1 + ( 7 - 1 ) d = 27
a1 + 6 d = 27
Now you must solve system:
a1 + 3 d = 15
a1 + 6 d = 27
___________
Try to solve it.
The solution is a1 = 3 , d = 4
Yours A.P.
3 , 7 , 11 , 15 ,19 , 23 , 27...
an = a1 + ( n - 1 ) d
where
a1 = the initial term
d = the common difference of successive members is d,
an = the nth term
In this case:
a4 = a1 + ( 4 - 1 ) d = 15
a1 + 3 d = 15
a7 = a1 + ( 7 - 1 ) d = 27
a1 + 6 d = 27
Now you must solve system:
a1 + 3 d = 15
a1 + 6 d = 27
___________
Try to solve it.
The solution is a1 = 3 , d = 4
Yours A.P.
3 , 7 , 11 , 15 ,19 , 23 , 27...
2 answers