The 5th and the 12th terms of an A.P series are 14 and 25 respectively. Find the first and the common difference.?
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Answer: d=11/7;a=54/7
Step-by-step explanation:
Given :
t5=14 ; t12=25
tn=a+(n-1)d
a+(5-1)d=14
a+4d=14 ----- (i)
Also a +(12-1)d=25
a+11d=25 ---(ii)
Equation (ii)-(i)
a+11d-a-4d=25-14
7d=11
d=11/7
Now Substituting value of d in Equation (i)
a+4*(11/7)=14
a=14-44/7=(98-44)/7=54/7
d=11/7;a=54/7
mayankdude:
u did wrong, see your steps
where you eliminated
Equation (ii)-(i) is Nothing But Elimination Right?
Answered by
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The fifth term of AP is 14.
so, a + 4d = 14. ....( eq. 1)
The twelve term of AP is 25 .
so, a +11d= 25 ......(eq. 2)
From equation one and 2:
we get the above picture by eliminating method
so, a + 4d = 14. ....( eq. 1)
The twelve term of AP is 25 .
so, a +11d= 25 ......(eq. 2)
From equation one and 2:
we get the above picture by eliminating method
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