β Pehle Yeh Aata Hai?
Yeh post shuru karne se pehle, in teen sawaalon ko 1 minute mein khud try kijiye:
- 5 Γ 10 = ?
- Like terms kya hote?
- a Γ a ko kaise likhte?
Answers dekho
- 50
- Same letter-numbers wale (3x, 5x)
- aΒ²
Teeno sahi? Badhiya, aage chaliye! Koi galat hua? Koi baat nahi, Book 1 Ch 2 (exponents) aur Ch 5 dekh lijiye.
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π¬ Kahani: Tiffin Ki Dukaan Ka Hisaab
Sonu ki maa tiffin service chalaati hain. Har tiffin mein 6 roti aur 4 sabzi-katori. Aaj 5 tiffin bane. Sonu ne gina: β6 + 4 = 10 cheezein, 10 Γ 5 = 50.β π±
Maa ne alag gina: βRoti 5 Γ 6 = 30, katori 5 Γ 4 = 20, kul 50.β Dono ka jawab same!
Kya yeh sanyog hai? Nahi, yahi hai distributive property: guna ko tukdon mein baant do, phir jodo. Aaj iska βkyunβ chitra se samjhenge. π§
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π Concept: Guna = Area; Area Ko Tukdon Mein Baanto
π‘ Is post ki ek badi baat: a Γ (b + c) ek rectangle ka area hai jiski chaudaai (b + c). Use do tukdon mein kaato: a Γ b aur a Γ c. Tukdon ka jod = poora area. Isliye a(b + c) = ab + ac, har number ke liye. Poora chapter isi ek idea pe khada hai.
Step 1: Chitra: dots ya area
5 panktiyaan, 6 + 4 = 10 khol. Poora: 5 Γ 10 = 50. Tukde: 30 + 20 = 50 β
WHY kaam karta? Rectangle kaatne se koi dot gayab nahi hota, na naya aata. Bas do baar mein gine.
Step 2: Ghataav pe bhi: a(b β c) = ab β ac
7 Γ 48 = 7 Γ (50 β 2) = 350 β 14 = 336.
WHY? 50 khol ka rectangle banao, phir 2 khol ka tukda hata do. Hataaya hua area = 7 Γ 2.
Step 3: Ulta bhi: (a + b)c = ac + bc
(a + b)c = c(a + b) (guna ka kram badal sakte) = ca + cb = ac + bc.
Rectangle ko khada kaato ya leta, baat ek hi.
Step 4: Bracket mein kai terms
4a(3a β 2b + 5) = 4a Γ 3a β 4a Γ 2b + 4a Γ 5 = 12aΒ² β 8ab + 20a.
Har term ko bahar wale se guna karo, sign ke saath. Phir dekho: koi like terms? Yahan nahi (aΒ², ab, a sab alag).
Step 5: Ulta chalna: common nikaalo (factor)
6x + 9y = 3(2x + 3y). Distributive ko ulta padha: dono terms mein 3 common.
Kab kaunsa? Hisaab aasaan karna ho to kholo (7 Γ 48). Expression chhota karna ho ya divisibility dikhani ho to common nikaalo (Ch 5 ka 6a + 6b = 6(a + b) yaad?).
πͺ Atak Gaye? Aise Socho
- Bracket ke bahar wala number/letter pehchaano.
- Andar ke har term pe ek-ek teer banao.
- Har teer pe guna karo, sign saath le jaao.
- Like terms jodo.
- Ek chhoti value (a = 1, b = 2) daal ke dono taraf check karo.
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π Deep Concept: Distributive: Jod Aur Guna Ka Pul
Jod aur guna do alag operation hain. Distributive property batati hai woh aapas mein kaise milte: guna, jod ke upar βbaantβ jaata hai.
Par ulta nahi! Jod guna pe nahi baant-ta: 2 + (3 Γ 4) = 14, par (2 + 3) Γ (2 + 4) = 30 β. Aur guna guna pe bhi nahi: 2 Γ (3 Γ 4) = 24, par (2 Γ 3) Γ (2 Γ 4) = 48 β.
Itihaas: Brahmagupta (628 CE) ne BrΔhmasphuαΉasiddhΔnta mein ise khaαΉαΈa-guαΉanam (tukdon mein guna) kaha: βGuna karne wale ko tukdon mein todo jinka jod wahi ho, har tukde se guna karo, aur jodo.β Euclid ne isse geometry mein, Aryabhata ne algebra mein istemaal kiya.
Unifying idea: mushkil guna = aasaan tukde. Aage ke saare identities, (a + b)Β², fast multiplication, sab isi ek pul pe chalte hain. π―
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βοΈ Solved Examples
Example 1 (Easy): 9 Γ 104 mann mein.
9 Γ (100 + 4) = 900 + 36 = 936.
Check: 936 Γ· 9 = 104 β
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Example 2 (Medium): β3p(2p β 5q + 1) kholo.
β3p Γ 2p = β6pΒ², β3p Γ (β5q) = +15pq, β3p Γ 1 = β3p β β6pΒ² + 15pq β 3p.
Check: p = 1, q = 1: baayan β3(2 β 5 + 1) = 6; daayan β6 + 15 β 3 = 6 β
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Example 3 (NCERT style): 17 Γ 6 + 17 Γ 4 sabse aasaan tareeke se.
Ulta distributive: 17 Γ (6 + 4) = 17 Γ 10 = 170.
Check: 102 + 68 = 170 β
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Sonu aur maa: dono sahi the. Sonu ne poora rectangle gina (5 Γ 10), maa ne tukde (30 + 20). Agle din 12 tiffin: maa ne turant kaha β72 roti, 48 katori, 120 cheezeinβ! π±
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π Distributive Property Roz Ki Zindagi Mein
- π Shopping: 4 kilo seb βΉ98 kilo: 4 Γ 100 β 4 Γ 2 = βΉ392.
- π School kit: 30 bachche, har ek ko 2 copy + 1 pen: 30 Γ 2 + 30 Γ 1 = 90 cheezein.
- π Ghar ka farsh: L-shape kamra = do rectangles ke area ka jod.
- π¬ Mithai ke dabbe: 8 dabbe, har ek mein 12 laddoo + 6 barfi = 8 Γ 18 = 144.
- π° Salary: 25 din Γ (βΉ400 + βΉ50 bonus) = 25 Γ 400 + 25 Γ 50.
Dukaandaar roz yeh karte: ββΉ99 Γ 6? 600 β 6 = βΉ594!β Distributive = mental maths ka superpower. πͺ
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π§ Kab Use Karein, Kab Nahi
| Situation | Kya karein | Kyun |
|---|---|---|
| Hisaab aasaan karna | β Kholo (7 Γ 48 = 7 Γ 50 β 7 Γ 2) | Paas ka gol number |
| Expression chhota karna | β Common nikaalo | Ulta distributive |
| Kai terms bracket mein | β Har term ko guna | Sign dhyaan |
| Jod guna pe? | β Nahi baant-ta | 2 + 3 Γ 4 |
| Guna guna pe? | β Nahi | 2(3 Γ 4) β 6 Γ 8 |
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βββ Worked Mistake
Sawaal: 5(2x + 3) kholo.
β Galat: 10x + 3. Sirf pehle term ko guna kiya!
β Sahi: 5 Γ 2x + 5 Γ 3 = 10x + 15. Check: x = 1: 5 Γ 5 = 25; 10 + 15 = 25 β
Doosri common galti: β2(a β 3) = β2a β 6. Sign! β2 Γ (β3) = +6 β β2a + 6.
π§ Rule of thumb: Bahar wala andar ke HAR term se milta hai, sign ke saath.
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π 10 MCQs
Q1. 6(a + 7) = ?
Solution dekho
Sahi jawab: (b)
- (a) galat: 7 ko bhi 6 se guna karna tha.
- (b) sahi: 6 Γ a + 6 Γ 7 = 6a + 42 β
- (c) galat: a ko bhi 6 se guna karna tha.
- (d) galat: 6 aur 7 jodna galat hai.
Q2. 8 Γ 97 aasaan tareeke se?
Solution dekho
Sahi jawab: (a)
- (a) sahi: 8 Γ (100 β 3) = 800 β 24 β
- (b) galat: 3 ko bhi 8 se guna karna tha.
- (c) galat: Yeh tukde 97 nahi banaate.
- (d) galat: 97 = 100 β 3, plus nahi.
Q3. β4(x β 2) = ?
Solution dekho
Sahi jawab: (b)
- (a) galat: β4 Γ β2 = +8, minus nahi.
- (b) sahi: β4 Γ β2 = +8, to β4x + 8 β
- (c) galat: x ka sign ulta ho gaya.
- (d) galat: 2 ko bhi β4 se guna karna tha.
Q4. 2a(3a + b) = ?
Solution dekho
Sahi jawab: (b)
- (a) galat: 2a Γ 3a = 6aΒ², sirf 6a nahi.
- (b) sahi: Sahi jawab: 2a Γ 3a + 2a Γ b β
- (c) galat: 2 Γ 3 = 6, jod nahi, isliye yeh galat.
- (d) galat: b ko bhi 2a se guna karna tha.
Q5. 12x + 18 = ?
Solution dekho
Sahi jawab: (a)
- (a) sahi: Sahi jawab: Common 6 nikaala β
- (b) galat: 18 Γ· 6 = 3 hona chahiye.
- (c) galat: 18 Γ· 3 = 6 hona chahiye.
- (d) galat: 18 Γ· 12 = 18 nahi hota.
Q6. 2 + (3 Γ 4) = (2 + 3)(2 + 4)?
Solution dekho
Sahi jawab: (b)
- (a) galat: 14 aur 30 alag hain, isliye yeh galat.
- (b) sahi: Jod guna pe nahi baant-ta β
- (c) galat: Yahan to bilkul nahi, isliye yeh galat.
- (d) galat: Integers mein bhi nahi.
Q7. KhaαΉαΈa-guαΉanam kisne likha?
Solution dekho
Sahi jawab: (a)
- (a) sahi: BrΔhmasphuαΉasiddhΔnta (628 CE) β
- (b) galat: Euclid ne geometry mein use kiya.
- (c) galat: Newton bahut baad mein aaye.
- (d) galat: Pascal ka yeh kaam nahi tha.
Q8. 23 Γ 7 + 23 Γ 3?
Solution dekho
Sahi jawab: (a)
- (a) sahi: Sahi jawab: 23 Γ (7 + 3) = 230 β
- (b) galat: 161 sirf 23 Γ 7 hai, isliye yeh galat.
- (c) galat: 69 sirf 23 Γ 3 hai, isliye yeh galat.
- (d) galat: 253 = 23 Γ 11 hota, 23 Γ 10 nahi.
Q9. 3(2x β y + 4) mein y ka term?
Solution dekho
Sahi jawab: (a)
- (a) sahi: Sahi jawab: 3 Γ (βy) = β3y β
- (b) galat: y ko bhi 3 se guna karna tha.
- (c) galat: Sign minus hai, plus nahi.
- (d) galat: Letter y bhi chahiye, isliye yeh galat.
Q10. Rectangle 5 Γ (6 + 4) ke tukde?
Solution dekho
Sahi jawab: (a)
- (a) sahi: Sahi jawab: 5 Γ 6 aur 5 Γ 4 β
- (b) galat: Yeh jod hain, guna nahi.
- (c) galat: 4 ko bhi 5 se guna karna tha.
- (d) galat: Yeh area nahi, lambaai hai.
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β FAQs (Bachchon Ke Asli Sawaal)
1. Distributive property ka naam kyun?
Bahar ka guna andar ke har term pe βbaantβ (distribute) diya jaata hai.
2. Kya negative numbers pe bhi?
Haan: x(y + z) = xy + xz sab integers (aur fractions) pe sach.
3. Bhaag pe?
(a + b) Γ· c = a Γ· c + b Γ· c sach. Par c Γ· (a + b) β c Γ· a + c Γ· b.
4. Identity kya hai?
Aisi barabari jo letters ki har value pe sach ho, jaise a(b + c) = ab + ac.
5. Chitra kyun zaroori?
Chitra se βkyunβ dikhta: area tukdon mein baant-ta hai. Formula bhool jao, chitra yaad rahega.
6. Aage kya?
Do brackets ka guna (a + m)(b + n): Post 2 β Guna Mein Badlaav: Increments.
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ποΈ Practice Zone (12 Sawaal)
Q1. Easy 7(x + 5) kholo.
Solution dekho
7x + 35. Check: x = 1 β 42 β
Q2. Easy 6 Γ 103 mann mein.
Solution dekho
600 + 18 = 618. Check β
Q3. Easy 15a + 20 mein common nikaalo.
Solution dekho
5(3a + 4). Check: a = 1 β 35 β
Q4. Easy 9 Γ 49?
Solution dekho
450 β 9 = 441. Check: 21Β² = 441 β
Q5. Medium β5(2y β 3) kholo.
Solution dekho
β10y + 15. Check: y = 1 β 5 β
Q6. Medium 3x(x β 4y + 2) kholo.
Solution dekho
3xΒ² β 12xy + 6x. Check: x = 1, y = 1 β β3 β
Q7. Medium 46 Γ 25 + 54 Γ 25?
Solution dekho
25 Γ 100 = 2500. Check β
Q8. Medium 2(3a + 1) + 4(a β 2) saral karo.
Solution dekho
6a + 2 + 4a β 8 = 10a β 6. Check: a = 1 β 4 β
Q9. NCERT style (2/3)(9a β 6b + 12) kholo.
Solution dekho
6a β 4b + 8. Check: a = b = 1 β 10 β
Q10. NCERT style 999 Γ 7 mann mein.
Solution dekho
7000 β 7 = 6993. Check β
Q11. NCERT style a(b β c) + b(c β a) + c(a β b) = ?
Solution dekho
Sab kat jaata β 0. Check: a = 1, b = 2, c = 3 β β1 + 4 β 3 = 0 β
Q12. NCERT style xΒ² + 5x mein common nikaalo.
Solution dekho
x(x + 5). Check: x = 2 β 14 β
Answer Key β charumam.com exclusive
π§ HOTS (Sochne Wale Sawaal)
Q1. Kya (a + b) Γ· c = a Γ· c + b Γ· c? Aur c Γ· (a + b)?
Solution dekho
Pehla haan, doosra nahi: 12 Γ· (2 + 4) = 2, par 6 + 3 = 9. Check β
Q2. L-shape: 8 Γ 10 ka rectangle jisme 3 Γ 4 ka kona kata. Area do tareeke se?
Solution dekho
80 β 12 = 68; ya tukde 8 Γ 6 + 5 Γ 4 = 48 + 20 = 68. Check β
Q3. n(n + 1) β n(n β 1) = ?
Solution dekho
nΒ² + n β nΒ² + n = 2n. Check: n = 3 β 12 β 6 = 6 β
Q4. Kya distributive se dikhao ki 3 lagaataar numbers ka jod 3 ka multiple?
Solution dekho
(n β 1) + n + (n + 1) = 3n = 3 Γ n. Check: 4 + 5 + 6 = 15 β
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π Olympiad Corner
Q1. 37 Γ 27 + 37 Γ 73?
Solution dekho
3700.
Q2. 125 Γ 32 mann mein?
Solution dekho
125 Γ 8 Γ 4 = 4000.
Q3. a = 2, b = 3: 4a(b β a) + 2b(a + b)?
Solution dekho
8 + 30 = 38.
Q4. 9999 Γ 12?
Solution dekho
119988.
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π CharuMam Motivation
Sonu ne seekha: ek hi cheez ko do tarah se ginna, aur dono ka same aana: yahi maths ki khoobsurti hai. Aage har identity isi se niklegi! π
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π’ Master Recap
- π‘ Chaabi: a Γ (b + c) ek rectangle ka area hai jiski chaudaai (b + c). Use do tukdon mein kaato: a Γ b aur a Γ c. Tukdon ka jod = poora area. Isliye a(b + c) = ab + ac, har number ke liye. Poora chapter isi ek idea pe khada hai.
- a(b + c) = ab + ac (area ka chitra).
- a(b β c) = ab β ac.
- Bracket ke har term ko guna, sign ke saath.
- Ulta: common nikaalo.
- Jod guna pe nahi baant-ta.
- Brahmagupta: khaαΉαΈa-guαΉanam.
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π Aage Kya?
Ek number badhe to guna kitna badhta? Agla post: Post 2 β Guna Mein Badlaav: Increments.
Koi doubt? CharuMam AI Tutor se poochho, ya comment mein likho! π¬
