How many terms of A.ap,2,4 6....must be taken do that their sum is 156 ? explain it properly
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here a= 2
d=2
now Sn= 156
Sn= n/2 {2a+(n-1)d}
now putting the values of a and d and Sn
156=n/2 {2×2 +(n-1) 2}
156×2= n{4+2n-2}
312 = n{2+2n}
312 = 2n + 2n^2
312 = 2 (n+n^2)
312/2 = n+ n^ 2
156 = n + n^2
now by quadratic formula or mid term splitting
you will get 2 answers
first one is -12 and the second one is +13
so the correct answer is +13
n^2 means n ki power 2 ..
I hope it will help u
d=2
now Sn= 156
Sn= n/2 {2a+(n-1)d}
now putting the values of a and d and Sn
156=n/2 {2×2 +(n-1) 2}
156×2= n{4+2n-2}
312 = n{2+2n}
312 = 2n + 2n^2
312 = 2 (n+n^2)
312/2 = n+ n^ 2
156 = n + n^2
now by quadratic formula or mid term splitting
you will get 2 answers
first one is -12 and the second one is +13
so the correct answer is +13
n^2 means n ki power 2 ..
I hope it will help u
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