Determine the nth term of the AP whose 7th term is -1 and 16th term is 17
atharva88:
please solve my question at the time of marriage the man was 6 years older than his wife, but 12 years after his marriage his age was 6/5th of the age of the wife. what were their ages at the time of marriage?
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Answered by
39
t7 = -1 eq 1
t16 =17 eq2
.in eq 1
we can write t7 that is seventh term in another way using a formula
that is tn = a + (n-1)d
so a +(7-1)d=-1
a +6d=-1 eq 3
in eq 2
t16 = 17
a+15d =17 eq4
now subtract eq 3 and eq4
a+ 6d = -1
-a-15d=-17
__________
-9d =-18
__________
so d = 2
them substitute d = 2 in in any equation
but I am substituting it in eq 3
a + 6(2) = -1
a = -13
now
the question is to find tn
so
tn = a+(n-1)d
tn= -13 + (n-1)2
tn = -13 +2n-2
tn = 2n-15
_________
hope this helps you
t16 =17 eq2
.in eq 1
we can write t7 that is seventh term in another way using a formula
that is tn = a + (n-1)d
so a +(7-1)d=-1
a +6d=-1 eq 3
in eq 2
t16 = 17
a+15d =17 eq4
now subtract eq 3 and eq4
a+ 6d = -1
-a-15d=-17
__________
-9d =-18
__________
so d = 2
them substitute d = 2 in in any equation
but I am substituting it in eq 3
a + 6(2) = -1
a = -13
now
the question is to find tn
so
tn = a+(n-1)d
tn= -13 + (n-1)2
tn = -13 +2n-2
tn = 2n-15
_________
hope this helps you
wrong answer
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Answered by
10
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