Class 7th Math Ex-1.1 Solved By PREM SIR

✅ Question 1:

Kya bola gaya hai?
Aise do numbers likhne hain:

(a) jinka sum (योगफल) –7 ho

(b) jinka difference (अंतर) –10 ho

(c) jinka sum 0 ho


🟢 Answer:

(a) –5 + (–2) = –7
👉 Negative numbers ka addition hamesha aur zyada negative hota hai.

(b) –2 – 8 = –10
👉 Jab ek number se bada negative subtract karte hain, result aur zyada negative hota hai.

(c) +5 + (–5) = 0
👉 Jab ek positive aur same value ka negative number add karte hain, answer 0 aata hai.

📚 Key point:

> Jab number ke aage “+” likha hai matlab wo positive hai, aur “–” ka matlab negative.




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✅ Question 2:

Kya bola gaya hai?

(a) Do negative integers jinka difference 8 ho.

(b) Ek negative aur ek positive integer likhna hai jinka sum –5 ho.

(c) Ek positive aur ek negative integer likhna hai jinka difference –3 ho.


🟢 Answer:

(a) –2 – (–10) = –2 + 10 = 8
👉 Jab kisi number se negative minus karte hain, toh wo positive ban jata hai.

(b) (–7) + 2 = –5
👉 Negative bada hai, isliye total negative aaya.

(c) (–2) – 1 = –2 –1 = –3
👉 Jab negative se aur subtract karte hain, aur negative hota hai.


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✅ Question 3:

Situation:
Ek quiz mein team A ka score tha: –40, 10, 0
Team B ka score tha: 10, 0, –40

Pucha gaya hai:
Kis team ka total score zyada hai?
Kya integers ko kisi bhi order mein jod sakte hain?

🟢 Answer:

Team A: –40 + 10 + 0 = –30
Team B: 10 + 0 + (–40) = –30

👉 Dono ka total same aaya!

📌 Conclusion:
Yes! Integers ko kisi bhi order mein jod sakte hain
Ye hota hai: “Commutative Property” of addition


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✅ Question 4:

Fill in the blanks and name the property used:

🟢 Answers + Explanation:

(i) (–5) + (+8) = (+8) + (–5)
🧠 Commutative Property
👉 Order badalne par addition ka result same rehta hai.


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(ii) –53 + 0 = –53
🧠 Zero Additive Property
👉 Kisi bhi number mein 0 jodne par number same rehta hai.


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(iii) 17 + (–17) = 0
🧠 Additive Identity
👉 Kisi number ka ulta (opposite) add karne par answer 0 aata hai.


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(iv) [13 + (–12)] + (–7) = 13 + [(–12) + (–7)]
🧠 Associative Property
👉 Bracket kahin bhi lagao, answer same aata hai.


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(v) (–4) + [15 + (–3)] = [–4 + 15] + (–3)
🧠 Associative Property
👉 Bracket ke grouping ka order change karo, answer par fark nahi padta.


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🔚 Final Summary for Bachchon ke Liye:

Property Name Hinglish Trick

Commutative Property Order badlo, answer same
Zero Additive 0 jodne se number change nahi hota
Additive Identity Number + uska opposite = 0
Associative Property Bracket kahin bhi lagao, result same
Integers Exercise 1.1 - Prem Eternal Education

🔢 Integers – Exercise 1.1

👨‍🏫 Coaching: Prem ♾️ Eternal Education

📞 Contact: 6200409895

🟣 Question 1:

Write down a pair of integers whose:
  • (a) sum is –7
  • (b) difference is –10
  • (c) sum is 0
  • (a) –5 + (–2) = –7
  • (b) –2 – 8 = –10
  • (c) +5 + (–5) = 0

🟣 Question 2:

  • (a) Write a pair of negative integers whose difference is 8
  • (b) Write a negative and a positive integer whose sum is –5
  • (c) Write a positive and a negative integer whose difference is –3
  • (a) –2 – (–10) = –2 + 10 = 8
  • (b) (–7) + 2 = –5
  • (c) (–2) – 1 = –3

🟣 Question 3:

In a quiz, team A scores –40, 10, 0 and team B scores 10, 0, –40. Which team scored more? Can we add integers in any order?

Team A: –40 + 10 + 0 = –30

Team B: 10 + 0 + (–40) = –30

✅ Total score same. Yes, we can add integers in any order — Commutative Property applies.

🟣 Question 4:

Fill in the blanks to make the following statements true:
  • (i) (–5) + (+8) = (+8) + (……)
  • (ii) –53 + …… = –53
  • (iii) 17 + …… = 0
  • (iv) [13 + (–12)] + (……) = 13 + [(–12) + (–7)]
  • (v) (–4) + [15 + (–3)] = [–4 + 15] + ……
  • (i) (–5) + (+8) = (+8) + (–5) ✅ Commutative Property
  • (ii) –53 + 0 = –53 ✅ Zero Additive Property
  • (iii) 17 + (–17) = 0 ✅ Additive Identity
  • (iv) [13 + (–12)] + (–7) = 13 + [(–12) + (–7)] ✅ Associative Property
  • (v) (–4) + [15 + (–3)] = [–4 + 15] + (–3) ✅ Associative Property

📚 Summary of Properties:

Property Explanation (Hinglish)
Commutative Property Order badalne par answer same aata hai (a + b = b + a)
Zero Additive Property Kisi number mein 0 add karo, answer wahi rehta hai
Additive Identity Number + uska opposite = 0
Associative Property Bracket kahin bhi lagao, answer same hi aata hai

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