Triples Ki Trick Aur Fermat Ki Paheli | Class 8 Maths Book 2 Ch 2

📘 Class 8 · Ganita Prakash Book 2Ch 2 · Baudhayana–Pythagoras TheoremPost 7 / 8⏱ 25–30 min
Triples Ki Trick Aur Fermat Ki Paheli 🧩

✅ Pehle Yeh Aata Hai?

Yeh post shuru karne se pehle, in teen sawaalon ko 1 minute mein khud try kijiye:

  1. 1 + 3 + 5 kitna hai?
  2. 9 kis number ka square hai?
  3. Kya (3, 4, 5) primitive triple hai?
Answers dekho
  1. 9
  2. 3 (3 × 3 = 9)
  3. Haan, koi common factor nahi

Teeno sahi? Badhiya! Triple aur primitive ka matlab bhool gaye? Post 6 — Baudhayana Triples Kya Hain? dekh lijiye.

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🎬 Kahani: Kanche Ki Chaukor Jamaavat

Priya kanche (marbles) se chaukor bana rahi thi. 1 kancha = 1 × 1 ka chaukor. Use 2 × 2 banane ke liye 3 aur chahiye the. 3 × 3 ke liye 5 aur. 4 × 4 ke liye 7 aur!

“Arre! Har baar agla odd number jud raha hai: 1, 3, 5, 7…” Priya chillaayi.

Rohan bola, “To 1 + 3 + 5 + 7 = 16 = 4². Mazedaar! Par isse kya milega?”

Priya ki aankhein chamki: “Agar jo odd number jud raha hai woh khud ek square ho, to… do squares ka jod ek square! Yaani triple!” 🤯

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📖 Concept: Odd Numbers Se Triples Banao

Step 1: Pehle n odd numbers ka jod = n²

1 = 1², 1 + 3 = 4 = 2², 1 + 3 + 5 = 9 = 3², 1 + 3 + 5 + 7 = 16 = 4²…

WHY? Kanche ki tarah: (n − 1) × (n − 1) ke chaukor ko n × n banane ke liye ek “L” jodna padta hai jisme (n − 1) + (n − 1) + 1 = 2n − 1 kanche hain, jo n-va odd number hai.

Step 2: Isse niyam

(n − 1)² + (2n − 1) = n²

Jaise n = 5: 4² + 9 = 16 + 9 = 25 = 5² ✅

Step 3: Jab (2n − 1) khud ek square ho

Agar 2n − 1 = m² (koi odd square), to (n − 1)² + m² = n², yaani (m, n − 1, n) ek triple!

Odd square m²2n − 1 = m² → nTriple (m, n − 1, n)
9 (m = 3)n = 5(3, 4, 5)
25 (m = 5)n = 13(5, 12, 13)
49 (m = 7)n = 25(7, 24, 25)
81 (m = 9)n = 41(9, 40, 41)
121 (m = 11)n = 61(11, 60, 61)

Shortcut: odd m lo, n = (m² + 1) ÷ 2. Triple = (m, n − 1, n).

WHY anant triples? Odd numbers anant hain, to odd squares bhi, to triples bhi anant! ♾️

Step 4: Yeh trick hamesha primitive deti hai

Isme hypotenuse n aur ek leg n − 1 lagaataar numbers hain. Lagaataar numbers ka koi common factor (1 ke alaawa) nahi hota, to triple hamesha primitive.

Step 5: Par sab primitive nahi milte

Is trick mein hypotenuse aur ek leg mein farak 1 hota hai. (8, 15, 17) mein farak 2, (20, 21, 29) mein 8, (12, 35, 37) mein 2. Yeh primitive hain par is trick se nahi milte.

WHY jaanna zaroori? Har tareeke ki ek seema hoti hai. Achha ganitagya poochhta hai: “Mera tareeka kya-kya nahi deta?”

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🔐 Deep Concept: 350 Saal Ki Paheli: Fermat Ka Last Theorem

Hum ne dekha: 1 + 3 + … + 25 = 13² aur 12² + 5² = 13². Squares ke jod ke anant hal hain.

Fransisi ganitagya Pierre de Fermat ne socha: kya cubes ke saath bhi aisa ho sakta hai, x³ + y³ = z³? Ya 4th power? Unka daawa:

xⁿ + yⁿ = zⁿ ka n > 2 ke liye koi hal nahi (natural numbers mein)

Fermat ne ek kitaab ke haashiye (margin) mein likha ki unke paas iska “adbhut saboot” hai, par haashiya chhota hai! 😅 Woh saboot kabhi mila nahi, aur 300 saal se zyada duniya ke bade-bade ganitagya haar gaye.

1963 mein 10 saal ke Andrew Wiles ne library mein Eric Temple Bell ki kitaab The Last Problem padhi aur thaan liya ki ise hal karenge. Saalon ki mehnat ke baad, 1994 mein unhone ise prove kar diya! 🏆 🔐

sirf charumam.com readers ke liye 🔐

✏️ Solved Examples

Example 1 (Easy): m = 13 se trick lagao.

m² = 169. n = (169 + 1) ÷ 2 = 85. Triple = (13, 84, 85).

WHY sahi hai? 169 + 7056 = 7225 = 85² ✅

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Example 2 (Medium): m = 15 se triple banao aur check karo primitive hai.

225 → n = 113. Triple (15, 112, 113). 112 aur 113 lagaataar, to primitive.

WHY sahi hai? 225 + 12544 = 12769 = 113² ✅

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Example 3 (NCERT style): 1 + 3 + 5 + … + 25 kitna hai? Isse kaun sa triple banta hai?

25 = 2 × 13 − 1, yaani 13 odd numbers. Jod = 13² = 169. Aakhri odd 25 = 5², to 12² + 5² = 13² → (5, 12, 13).

WHY sahi hai? 144 + 25 = 169 ✅

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Priya ka formula: “Odd m lo, (m² + 1) ÷ 2 = hypotenuse, usse 1 kam = doosra leg!” 🎉

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🏠 Real Life Mein

  • 🎲 Kanche/tile patterns: Har agla chaukor banane ke liye agla odd number.
  • 🏗️ Badi naap: (9, 40, 41) ya (11, 60, 61) se bade maidaan pe bhi bilkul 90° ka kona.
  • 🧠 Ganit ki duniya: Fermat ki paheli ne naye ganit ke kai hisse paida kiye, jo aaj computers aur codes mein kaam aate hain.
  • 📚 Prerna: Ek kitaab ne 10 saal ke bachche ko duniya ki sabse mushkil paheli hal karne ka sapna diya.

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🧭 Kab Use Karein, Kab Nahi

SituationKya kareinKyun
Naya primitive triple jaldi chahiye✅ Odd m lo, n = (m² + 1)/2Hamesha primitive
Hypotenuse − leg = 1 wala triple✅ Yahi trick(m, n − 1, n)
(8, 15, 17) jaisa chahiye❌ Yeh trick nahiFarak 2 hai; alag tareeka (Deep/HOTS dekho)
Cubes ka “triple”❌ Hal nahiFermat ka Last Theorem

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❌→✅ Worked Mistake

Sawaal: m = 4 (even) se trick lagao.

❌ Galat: “m² = 16, n = 17 ÷ 2 = 8.5, triple (4, 7.5, 8.5).”

Galti kya hai? 2n − 1 hamesha odd hai, to m² odd hona chahiye, yaani m odd. Even m pe n poora nahi aata ❌

✅ Sahi:

  • Is trick ke liye m = 3, 5, 7, 9… (odd) hi lo.
  • Even ke liye alag trick: (2k, k² − 1, k² + 1). k = 4 → (8, 15, 17) ✅

Yaad rakho: Har formula ki shartein padho!

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📝 10 MCQs

Q1. 1 + 3 + 5 + 7 + 9 = ?

(a) 20
(b) 25
(c) 30
(d) 16
Solution dekho

Sahi jawab: (b)

  • (a) galat: Jod dobara karo.
  • (b) sahi: 5 odd numbers → 5² = 25 ✅
  • (c) galat: Zyada hai.
  • (d) galat: 16 = pehle 4 ka jod.

Q2. (n − 1)² + (2n − 1) = ?

(a) n
(b) 2n
(c) n²
(d) (n + 1)²
Solution dekho

Sahi jawab: (c)

  • (a) galat: Square chahiye.
  • (b) galat: 2n nahi.
  • (c) sahi: Yahi niyam hai ✅
  • (d) galat: (n + 1)² = n² + 2n + 1.

Q3. m = 7 se triple?

(a) (7, 24, 25)
(b) (7, 23, 24)
(c) (7, 25, 26)
(d) (7, 48, 49)
Solution dekho

Sahi jawab: (a)

  • (a) sahi: n = 25, n − 1 = 24 ✅
  • (b) galat: 49 + 529 = 578 ≠ 576.
  • (c) galat: 49 + 625 ≠ 676.
  • (d) galat: n = 25 hona chahiye.

Q4. Yeh trick primitive kyun deti hai?

(a) n aur n − 1 lagaataar hain
(b) m even hai
(c) n bada hai
(d) Andaaza
Solution dekho

Sahi jawab: (a)

  • (a) sahi: Lagaataar numbers ka common factor sirf 1 ✅
  • (b) galat: m odd hota hai.
  • (c) galat: Size se fark nahi.
  • (d) galat: Saboot hai.

Q5. Kaun sa primitive triple is trick se NAHI milta?

(a) (3, 4, 5)
(b) (5, 12, 13)
(c) (8, 15, 17)
(d) (9, 40, 41)
Solution dekho

Sahi jawab: (c)

  • (a) galat: m = 3 se milta.
  • (b) galat: m = 5 se.
  • (c) sahi: 17 − 15 = 2, farak 1 nahi ✅
  • (d) galat: m = 9 se.

Q6. Fermat ka Last Theorem kya kehta hai?

(a) x² + y² = z² ka hal nahi
(b) n > 2 pe xⁿ + yⁿ = zⁿ ka natural hal nahi
(c) Har triple primitive
(d) √2 fraction nahi
Solution dekho

Sahi jawab: (b)

  • (a) galat: Squares ke to anant hal hain.
  • (b) sahi: Yahi ✅
  • (c) galat: Yeh galat bhi hai.
  • (d) galat: Yeh Euclid ka hai.

Q7. Fermat ka theorem kisne prove kiya?

(a) Euclid
(b) Baudhayana
(c) Andrew Wiles
(d) Pythagoras
Solution dekho

Sahi jawab: (c)

  • (a) galat: Euclid 300 BCE.
  • (b) galat: Baudhayana 800 BCE.
  • (c) sahi: 1994 mein ✅
  • (d) galat: Pythagoras 500 BCE.

Q8. Andrew Wiles ne yeh paheli hal karne ka sapna kis umar mein dekha?

(a) 10 saal
(b) 20 saal
(c) 40 saal
(d) 5 saal
Solution dekho

Sahi jawab: (a)

  • (a) sahi: 1963 mein, The Last Problem kitaab padh ke ✅
  • (b) galat: Tab tak woh sapna dekh chuke the.
  • (c) galat: 40 ki umar ke aas-paas to unhone saboot poora kiya (1994).
  • (d) galat: Itni chhoti umar ka zikr nahi hai.

Q9. m = 11 se hypotenuse?

(a) 60
(b) 61
(c) 121
(d) 66
Solution dekho

Sahi jawab: (b)

  • (a) galat: Yeh leg hai.
  • (b) sahi: (121 + 1)/2 = 61 ✅
  • (c) galat: Yeh m² hai.
  • (d) galat: Galat.

Q10. Kya trick se anant triples milte hain?

(a) Haan, odd numbers anant hain
(b) Nahi, 5 hi
(c) Sirf 100 tak
(d) Sirf ek
Solution dekho

Sahi jawab: (a)

  • (a) sahi: Har odd m > 1 se naya triple ✅
  • (b) galat: Anant hain.
  • (c) galat: Koi seema nahi.
  • (d) galat: Anant.

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❓ FAQs (Bachchon Ke Asli Sawaal)

1. Odd number kya hota hai?

Jo 2 se poora na bate: 1, 3, 5, 7…

2. Trick mein m = 1 lein to?

m² = 1 → n = 1 → (1, 0, 1). 0 positive nahi, to triple nahi. m = 3 se shuru karo.

3. Kya cubes ke liye koi triple nahi hai?

Haan, x³ + y³ = z³ ka natural numbers mein koi hal nahi (Fermat–Wiles).

4. Fermat kaun the?

17vi sadi ke French ganitagya. Unhone yeh daawa ek kitaab ke margin mein likha tha.

5. 300 saal kyun lage?

Saboot ke liye bilkul naye ganit ki zaroorat thi jo Fermat ke samay mein tha hi nahi.

6. Even legs wale triples kaise banayein?

(2k, k² − 1, k² + 1): k = 2 → (4, 3, 5); k = 4 → (8, 15, 17); k = 6 → (12, 35, 37).

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🏋️ Practice Zone (12 Sawaal)

Q1. Easy 1 se 19 tak ke odd numbers ka jod?

Solution dekho

10 numbers → 100.

Q2. Easy m = 9 se triple?

Solution dekho

(9, 40, 41).

Q3. Easy m = 13 se hypotenuse?

Solution dekho

85.

Q4. Easy 5 aur triples banao (NCERT idea).

Solution dekho

m = 11, 13, 15, 17, 19 → (11,60,61), (13,84,85), (15,112,113), (17,144,145), (19,180,181).

Q5. Medium Kya (17, 144, 145) check hota hai?

Solution dekho

289 + 20736 = 21025 = 145² ✅

Q6. Medium (2k, k² − 1, k² + 1) se k = 5?

Solution dekho

(10, 24, 26), yeh primitive nahi (2 common).

Q7. Medium Kya trick kabhi non-primitive deti hai?

Solution dekho

Nahi, n aur n − 1 lagaataar hain.

Q8. NCERT style Aise primitive triples batao jo trick se nahi milte.

Solution dekho

(8, 15, 17), (20, 21, 29), (12, 35, 37), (28, 45, 53).

Q9. NCERT style 1 + 3 + … + 49 kitna hai, aur kaun sa triple?

Solution dekho

25 numbers → 625 = 25². 49 = 7² → (7, 24, 25).

Q10. Medium 2n − 1 = 169 ho to n?

Solution dekho

85.

Q11. Medium Kya 2³ + 2³ kisi cube ke barabar hai?

Solution dekho

16, jo cube nahi (2³ = 8, 3³ = 27). Fermat sahi!

Q12. NCERT style (m, n − 1, n) mein hypotenuse aur bade leg ka farak?

Solution dekho

Hamesha 1.

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🧠 HOTS (Sochne Wale Sawaal)

Q1. Kya (2k, k² − 1, k² + 1) hamesha triple deta hai? Check k = 3.

Solution dekho

(6, 8, 10): 36 + 64 = 100 ✅. General: 4k² + (k² − 1)² = (k² + 1)².

Q2. Kanche wale chaukor ko 10 × 10 se 11 × 11 banane mein kitne kanche lagenge?

Solution dekho

2 × 11 − 1 = 21.

Q3. Golu: “x² + y² = z² ke anant hal hain, to x³ + y³ = z³ ke bhi honge.” Galti?

Solution dekho

Squares ka pattern cubes pe lagu nahi. Fermat–Wiles ne dikhaaya ki cubes ka koi natural hal nahi.

Q4. Kya koi triple hai jisme hypotenuse − leg = 1 aur chhota leg even ho?

Solution dekho

Nahi. m² = 2n − 1 odd hai, to m odd. Chhota leg m hamesha odd.

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🏆 Olympiad Corner

Q1. 1 + 3 + 5 + … + 99 = ?

Solution dekho

50 numbers → 2500.

Q2. Kitne triples (is trick se) mein hypotenuse 100 se kam hai?

Solution dekho

m = 3, 5, 7, 9, 11, 13 → n = 5, 13, 25, 41, 61, 85. 6.

Q3. (m, n − 1, n) mein agar m = 21 to legs ka jod?

Solution dekho

n = 221. Jod = 21 + 220 = 241.

Q4. n-va odd number 2n − 1 kyun hai?

Solution dekho

1 = 2(1) − 1, 3 = 2(2) − 1… har kadam 2 badhta hai, shuru 1 se.

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💗 CharuMam Motivation

Andrew Wiles ne 10 saal ki umar mein ek sapna dekha aur lagbhag 30 saal baad use poora kiya. 🏆

Aapke sapne ki koi umar nahi hoti, na koi deadline. Bas roz thoda-thoda, kanche ki tarah, ek-ek odd number jodte raho, ek din poora chaukor ban jaayega! 💫

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🟢 Master Recap

  • Pehle n odd numbers ka jod = n².
  • (n − 1)² + (2n − 1) = n².
  • 2n − 1 = m² (odd square) ho to (m, n − 1, n) triple. n = (m² + 1)/2.
  • Yeh trick hamesha primitive deti hai, par sab primitive nahi (jaise 8, 15, 17).
  • Fermat ka Last Theorem: n > 2 pe xⁿ + yⁿ = zⁿ ka natural hal nahi.
  • Andrew Wiles ne 1994 mein prove kiya.

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👉 Aage Kya?

Chapter ka aakhri post! Theorem ke asli duniya ke sawaal: Bhaskaracharya ka kamal (lotus) wala sawaal, rhombus, equilateral triangle ka area aur ek mazedaar rang wali paheli! 🪷

Koi doubt? CharuMam AI Tutor se poochho, ya comment mein likho! 💬

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