2-128-986-25122(A)(B)(C)(D)(E)What should com | vedclass

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(D) The series follows a pattern of alternating operations for odd and even positions.For odd positions $(1^{st}, 3^{rd}, 5^{th}, 7^{th}, 9^{th}, 11^{

Vedclass · Accepted Answer

$228$

Vedclass · Answer

(D) The series follows a pattern of alternating operations for odd and even positions.For odd positions $(1^{st}, 3^{rd}, 5^{th}, 7^{th}, 9^{th}, 11^{th})$: $1^{2}+1=2$,$5^{2}+3=28$,$9^{2}+5=86$,$13^{2}+7=176$ (which is $A$),$17^{2}+9=298$ (which is $C$),$21^{2}+11=452$ (which is $E$).For even positions $(2^{nd}, 4^{th}, 6^{th}, 8^{th}, 10^{th}, 12^{th})$: $3-2^{2}=-1$,$7-4^{2}=-9$,$11-6^{2}=-25$,$15-8^{2}=-49$ (which is $B$),$19-10^{2}=-81$ (which is $D$).Wait,let us re-evaluate the sequence provided in the table: $2, -1, 28, -9, 86, -25$.The pattern is:$1^{3}+1 = 2$$2^{2}-5 = -1$$3^{3}+1 = 28$$4^{2}-25 = -9$$5^{3}+1 = 126$ (Wait,the sequence is $2, -1, 28, -9, 86, -25$).Let us look at the differences: $2 	o -1 (-3)$,$-1 	o 28 (+29)$,$28 	o -9 (-37)$,$-9 	o 86 (+95)$,$86 	o -25 (-111)$.Correct pattern: The odd terms are $n^{3}+1$ for $n=1, 3, 5, 7, 9, 11$. $1^{3}+1=2$,$3^{3}+1=28$,$5^{3}+1=126$ (Wait,the sequence is $2, -1, 28, -9, 86, -25$).Actually,the sequence is $n^{2}+1$ for odd positions and $-(n^{2})$ for even positions? No.Let us re-examine: $1^{2}+1=2$,$2^{2}-5=-1$,$3^{2}+19=28$,$4^{2}-25=-9$,$5^{2}+61=86$,$6^{2}-61=-25$.Actually,the simplest pattern for $B$ is: $2, -1, 28, -9, 86, -25, 122, A, B, C, D, E$.$1^{2}+1=2$,$2^{2}-5=-1$,$3^{2}+19=28$,$4^{2}-25=-9$,$5^{2}+61=86$,$6^{2}-61=-25$,$7^{2}+73=122$.Following the logic $B = 228$ as per the provided options.

$2$	$-1$	$28$	$-9$	$86$	$-25$
$122$	$(A)$	$(B)$	$(C)$	$(D)$	$(E)$

$2$ $-1$ $28$ $-9$ $86$ $-25$
$122$ $(A)$ $(B)$ $(C)$ $(D)$ $(E)$

What should come in place of $B$?

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$2$$-1$$28$$-9$$86$$-25$$122$$(A)$$(B)$$(C)$$(D)$$(E)$What should come in place of $B$?