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Not your average video:
Interactive Problems: Solve problems alongside the video with step-by-step guidance and detailed solutions.
Exam Preparation: Complete unit reviews designed for final exam preparation with all key concepts covered systematically.
Expert Teaching: High-quality instruction from Perplex co-founder James Mullen with clear explanations, worked examples, and exam tips.
Sequences & Series
Watch comprehensive video reviews for Sequences & Series, designed for final exam preparation. Each video includes integrated problems you can solve alongside detailed solutions.
Not your average video:
Interactive Problems: Solve problems alongside the video with step-by-step guidance and detailed solutions.
Exam Preparation: Complete unit reviews designed for final exam preparation with all key concepts covered systematically.
Expert Teaching: High-quality instruction from Perplex co-founder James Mullen with clear explanations, worked examples, and exam tips.
Not your average video:
Interactive Problems: Solve problems alongside the video with step-by-step guidance and detailed solutions.
Exam Preparation: Complete unit reviews designed for final exam preparation with all key concepts covered systematically.
Expert Teaching: High-quality instruction from Perplex co-founder James Mullen with clear explanations, worked examples, and exam tips.
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SL Core 1.2
The sum of the first n terms in an arithmetic sequence is given by
or equivalently
Let's say you have the series 1+2+3+⋯+1000.
So the sum is 1001⋅500=500500.
In general, we have:
which gives the second formula Sn=2n(u1+un).
Example
Find the sum of the first 10 terms in the sequence 1,4,7…
We have u1=1, d=3 and n=10 so
SL Core 1.2
The sum of the first n terms in an arithmetic sequence is given by
or equivalently
Let's say you have the series 1+2+3+⋯+1000.
So the sum is 1001⋅500=500500.
In general, we have:
which gives the second formula Sn=2n(u1+un).
Example
Find the sum of the first 10 terms in the sequence 1,4,7…
We have u1=1, d=3 and n=10 so