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If (a_n=7n^2-3n+5), what is the value of (a_6)?
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Answer and explanation
Correct answer: 239
Substitute n=6: a_6=7(6)^2-3(6)+5=7×36-18+5=252-18+5=239. Therefore, 239 is correct. Option 252 is only the value of 7×6² and ignores the terms -3n+5. Exam tip: evaluate the exponent first, then perform multiplication and addition or subtraction.
Frequently asked questions
What is the correct answer to this question?
239
Why is this the correct answer?
Substitute n=6: a_6=7(6)^2-3(6)+5=7×36-18+5=252-18+5=239. Therefore, 239 is correct. Option 252 is only the value of 7×6² and ignores the terms -3n+5. Exam tip: evaluate the exponent first, then perform multiplication and addition or subtraction.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: nth term.
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