For what value n, the nth terms of AP's 59,61,63,...&-11,-4,3,10,...are equal
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Answered by
0
here ,
An = An'
a +( n-1)d = a' + (n-1)d'
so,
59 + (n-1)×2=-11 + (n-1)7
so, on solving...
5n = 75
n = 15
wish it helps ...
An = An'
a +( n-1)d = a' + (n-1)d'
so,
59 + (n-1)×2=-11 + (n-1)7
so, on solving...
5n = 75
n = 15
wish it helps ...
Answered by
0
1)59,61,63,.. ap
first term =a =59
Common difference=d=a2-a1=61-59=2
nth term an=a+(n-1)d
an=59+(n-1)2
an=59+2n-2=2n+57----(1)
2)-11,-4,3,10..., ap
a=-11
d= -4-(-11)=-4+11=7
an =-11+(n-1)7
an=-11+7n-7
an=7n-18---(2)
given (2)=(1)
7n-18=2n+57
7n-2n=57+18
5n=75
n=75/5
n=15
therefore
15th terms of both AP s are equal
first term =a =59
Common difference=d=a2-a1=61-59=2
nth term an=a+(n-1)d
an=59+(n-1)2
an=59+2n-2=2n+57----(1)
2)-11,-4,3,10..., ap
a=-11
d= -4-(-11)=-4+11=7
an =-11+(n-1)7
an=-11+7n-7
an=7n-18---(2)
given (2)=(1)
7n-18=2n+57
7n-2n=57+18
5n=75
n=75/5
n=15
therefore
15th terms of both AP s are equal
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