In an AP if the common difference (d) = - 4, and the seventh term (a7) is 4, then find the first term.
In an AP if the common difference (d) = - 4, and the seventh term (a7) is 4, then find the first term.
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Given d = -4 and a7 = 4
We know that nth terrn of A.P is
an = a +(n-1) d
a7 = a + (7 -1)d [ n = 7 ]
4 = a + 6 (-4)
.'. a = 4 + 24 = 28
.'. First term of an A.P = 28
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Given d = – 4 and a7 = 4
We know that nth term of AP is
an = a + (n – 1)d
a7 = a + (7 – 1)d [n = 7]
4 = a + 6(– 4)
a = 4 + 24 = 28
First term of an AP = 28
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