Watch comprehensive video reviews for most units, designed for final exam preparation. Each video includes integrated problems you can solve alongside detailed solutions.
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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 nth term in an arithmetic sequence is given by
where u1 is the first term and d is the common difference.
Example
An arithmetic sequence has u3=5 and u7=−7. Find the first term and the common difference.
We have u3=u1+2d=5 and u7=u1+6d=−7. Subtracting one from the other:
so d=−3. Thus u3=u1−6=5⇒u1=11
SL Core 1.2
The nth term in an arithmetic sequence is given by
where u1 is the first term and d is the common difference.
Example
An arithmetic sequence has u3=5 and u7=−7. Find the first term and the common difference.
We have u3=u1+2d=5 and u7=u1+6d=−7. Subtracting one from the other:
so d=−3. Thus u3=u1−6=5⇒u1=11