JEE 2023 — Mathematics PYQ
JEE | Mathematics | 2023Let s1,s2,s3,…,s10, respectively be the sum to 12 terms of 10 A.P.s whose first terms are 1,2,3,…,10 and the common differences are 1,3,5,…,19, respectively. Then, ∑i=110si.
Choose the correct answer:
- A.
7260
(Correct Answer) - B.
7380
- C.
7220
- D.
7360
7260
Explanation
1. General sum si ka formula
Kisi bhi ith A.P. ke liye sum ka formula hota hai:
si=2n[2ai+(n−1)di]
Yahan n=12 hai, toh:
si=212[2ai+(12−1)di]
si=6[2ai+11di]
2. Summation nikalna
Hume ∑i=110si nikalna hai:
i=1∑10si=i=1∑106[2ai+11di]
∑si=12i=1∑10ai+66i=1∑10di
3. Values put karna
-
∑ai: Ye 1 se 10 tak ka sum hai: 1+2+3+⋯+10=55.
-
∑di: Ye pehle 10 odd numbers ka sum hai: 1+3+5+⋯+19=102=100.
Ab in values ko equation mein rakhte hain:
∑si=12(55)+66(100)
∑si=660+6600
∑si=7260
Explanation
1. General sum si ka formula
Kisi bhi ith A.P. ke liye sum ka formula hota hai:
si=2n[2ai+(n−1)di]
Yahan n=12 hai, toh:
si=212[2ai+(12−1)di]
si=6[2ai+11di]
2. Summation nikalna
Hume ∑i=110si nikalna hai:
i=1∑10si=i=1∑106[2ai+11di]
∑si=12i=1∑10ai+66i=1∑10di
3. Values put karna
-
∑ai: Ye 1 se 10 tak ka sum hai: 1+2+3+⋯+10=55.
-
∑di: Ye pehle 10 odd numbers ka sum hai: 1+3+5+⋯+19=102=100.
Ab in values ko equation mein rakhte hain:
∑si=12(55)+66(100)
∑si=660+6600
∑si=7260

