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
0 reads0 ratings0 helpful

What is 2 times the difference between S_72 and S_36?

Answer and explanation

Correct answer: 3924

Use the governing identity S_n = n(n+1)/2. First calculate S_72 = 72 × 73/2 = 36 × 73 = 2628. Next, S_36 = 36 × 37/2 = 18 × 37 = 666. Their difference is S_72 − S_36 = 2628 − 666 = 1962. The wording asks for twice this difference, not merely the difference, so the required value is 2 × 1962 = 3924. Therefore option C is correct. A common distractor is 1962, which omits the final multiplication, while the nearby listed values can arise from an incorrect sum formula or a subtraction error. Keeping the order of operations clear gives the unique answer.

Related tags

MathematicsSequencesNatural-NumbersSum-DifferenceSum Of First N Natural NumbersSequences And ProgressionsClass 9 Mcq

Was this question useful?

No ratings yetWrite a review / Rate this question

Student Reviews

No published reviews yet.

Add Muft Shiksha to your Home Screen

In Safari, tap Share, then Add to Home Screen.