the 8th term of an ap is 32and its 12 term is 52.find ap
Answers
the first term is -3 and the common difference is 5
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GIVEN :
The 8th term of an AP is 32 .
The 12th term of an AP is 52.
TO FIND :
The AP
ANSWER :
The general term,tn =
where n is the nth term.
a is the first term.
d is the common difference.
t8 = a + ( 8 - 1) d
a + 7d = 32 ________(1)
t12 = a + (12 - 1) d
a + 11d = 52 _________(2)
Subtract (1) & (2) ,
(2) => a + 11d = 52
(1) => a + 7d = 32
(-) (-) (-)
_________________
4d = 20
d = 20/4
d = 5 .
Substitute the value of d = 5 in equation (1),,,,
(1) => a + 7 (5) = 32
a + 35 = 32
a = 32 - 35
a = -3
The general form of an AP is ,,,,,
AP = -3 + ( -3 + 5) + ( -3 + 2 ×5) + ....
AP = -3 + 2+ 7 +....
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