Practice - Second Problem: Sequences of 1s and -1s
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Practice Questions
Test your understanding with targeted questions
How many sequences are formed with 2 1s and 2 -1s?
💡 Hint: Think about choosing positions for 1s.
If a sequence has more -1s than 1s, is it valid?
💡 Hint: Recall the definition of valid sequences.
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Interactive Quizzes
Quick quizzes to reinforce your learning
What is the formula for the number of valid sequences with n 1s and n -1s?
💡 Hint: Think of how we derive valid counts.
True or False: If a sequence has an initial position with a negative sum, it is invalid.
💡 Hint: Refer back to the definition of valid sequences.
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Challenge Problems
Push your limits with advanced challenges
Find the number of valid sequences for n=4 and explain your approach.
💡 Hint: Make sure to outline both sets clearly.
Create a sequence of n=5 and justify its validity.
💡 Hint: Visualize how the sum changes as you construct the sequence step-by-step.
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Reference links
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