Muft Shiksha
Update

Muft Shiksha™ एक 100% Free Education Portal है 🇮🇳, जिसका उद्देश्य Class 9–12 के हर विद्यार्थी तक High-Quality Education को पूरी तरह मुफ्त पहुँचाना है। 🇮🇳 हम मानते हैं कि अच्छी शिक्षा किसी student की आर्थिक स्थिति पर निर्भर नहीं होनी चाहिए। 🇮🇳 हर विद्यार्थी को वही Quality Study Material, MCQs, Quizzes, Exam Preparation, Concept-Based Learning और Bilingual Support मिलना चाहिए, जो आमतौर पर महंगी Coaching या Premium Platforms में मिलता है। Muft Shiksha™ 🇮🇳 इसी सोच के साथ बनाया गया है

Subjects
Class 9MathematicsSequences and Progressionsnth termExpertLevel 58
0 reads0 ratings0 helpful

If (a_n=2n^2+9n-11), what is the value of (a_{10}-a_4)?

Advertisement

Answer and explanation

Correct answer: 222

Given \(a_n=2n^2+9n-11\), \(a_{10}=2(10)^2+9(10)-11=279\) and \(a_4=2(4)^2+9(4)-11=57\). Therefore, \(a_{10}-a_4=279-57=222\). The value 204 results from incorrectly calculating \(a_4\) as 75. Exam tip: substitute each value of \(n\) separately before finding the difference.

Related tags

Sequences And ProgressionsNth TermQuadratic SequenceSubstitutionAlgebra

Frequently asked questions

What is the correct answer to this question?

222

Why is this the correct answer?

Given \(a_n=2n^2+9n-11\), \(a_{10}=2(10)^2+9(10)-11=279\) and \(a_4=2(4)^2+9(4)-11=57\). Therefore, \(a_{10}-a_4=279-57=222\). The value 204 results from incorrectly calculating \(a_4\) as 75. Exam tip: substitute each value of \(n\) separately before finding the difference.

Which subject and chapter does this question cover?

This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: nth term.

Was this question useful?

No ratings yetWrite a review / Rate this question

Student Reviews

No published reviews yet.

KEEP PRACTISING

10 more MCQs
  1. 1In the sequence \((1,4,9,16,\ldots)\), what is the difference between the 15th term and the 14th term?
  2. 2What is the 25th term of the sequence \((-5,-1,3,7,\ldots)\)?
  3. 3If aₙ = n³ − n, what will be the value of a₇ − a₅?
  4. 4What will be the 12th term in the sequence (3, 5, 9, 15, 23, ...)?
  5. 5If a_n = n(n + 2), what will be the value of a_11 − a_8?
  6. 6If a_n = n^2 + 5n - 2, which term is equal to 148?
  7. 7The sequence (3, 8, 15, 24, …) has general term a_n = n² + 2n. Which term is 168?
  8. 8If a_n = n³ + n², what will be the value of a_6 − a_4?
  9. 9If a_n = 4n² − 1, which term is 575?
  10. 10If a_n = n(n + 3), which term is 130?
Advertisement