How many terms of a gp3
3*2,3*3 are needed to give the sum 120
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Hi Mate ! ! !
Let the no. of terms be n
Sum of n terms of g.p =. a ( r ^n - 1 ) / ( r -1 )
r = 3. sum of g.p = 120 and a = 3
so,
120. = 3( 3 ^n - 1 ) /2
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81 = 3^n
3 ^ 4. = 3 ^n
n = 4
Let the no. of terms be n
Sum of n terms of g.p =. a ( r ^n - 1 ) / ( r -1 )
r = 3. sum of g.p = 120 and a = 3
so,
120. = 3( 3 ^n - 1 ) /2
!!!!!!!!! Have a great future ahead!!!!!!!!!!!!
81 = 3^n
3 ^ 4. = 3 ^n
n = 4
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