The sum of six terms in an A.P is 75.The last term exceeds the first term by 15.Then the first term is
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Answered by
6
According to first condition,
S6 = 75
=> 6/2 [ 2a + (6-1)d] = 75
=> 3 [ 2a + 5d] = 75
=> 2a + 5d = 25 -------(1)
According to second condition,
T6 - T1 = 15
=> a + 5d - a = 15
=> 5d = 15
=> d = 3
On putting the value of d in equation 1, we get
2a + 5(3) = 25
=> 2a + 15 = 25
=> 2a = 10
=> a = 5
First term = 5
S6 = 75
=> 6/2 [ 2a + (6-1)d] = 75
=> 3 [ 2a + 5d] = 75
=> 2a + 5d = 25 -------(1)
According to second condition,
T6 - T1 = 15
=> a + 5d - a = 15
=> 5d = 15
=> d = 3
On putting the value of d in equation 1, we get
2a + 5(3) = 25
=> 2a + 15 = 25
=> 2a = 10
=> a = 5
First term = 5
Answered by
1
According to first condition,
S6 = 75
=> 6/2 [ 2a + (6-1)d] = 75
=> 3 [ 2a + 5d] = 75
=> 2a + 5d = 25 -------(1)
According to second condition,
T6 - T1 = 15
=> a + 5d - a = 15
=> 5d = 15
=> d = 3
On putting the value of d in equation 1, we get
2a + 5(3) = 25
=> 2a + 15 = 25
=> 2a = 10
=> a = 5
First term = 5
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