NCERT Class 7 Mathematics

ANSWERS 307

4. (i) 8 (ii) 4 (iii) 0 5. (i) –2 (ii) 2 (iii) 0 (iv) 2


5. (i) 5 x – 13; –3 (ii) 8x– 1; 15 (iii) 11x – 10; 12 (iv) 11x + 7; 29


6. (i) 2 x+4; 10(ii) – 4x + 6; –6 (iii) –5a + 6;11 (iv) – 8b + 6; 22 (v) 3a – 2b – 9; – 8


7. (i) 1000 (ii) 20 9. –5 10. 2 a^2 + ab + 3; 38

EXERCISE 12.4

1. Symbol Number of Digits Number of Segments

526

10 51

100 501

516

10 31

100 301

527

10 52

100 502

EXERCISE 13.1

1. (i) 64 (ii) 729 (iii) 121 (iv) 625


2. (i) 64 (ii) t^2 (iii) b^4 (iv) 5^2 × 7^3 (v) 2^2 × a^2 (vi) a^3 × c^4 × d


3. (i) 29 (ii) 7^3 (iii) 3^6 (iv) 5^5


4. (i) 34 (ii) 3^5 (iii) 2^8 (iv) 2^100 (v) 2^10


5. (i) 23 × 3^4 (ii) 5 × 3^4 (iii) 2^2 × 3^3 × 5 (iv) 2^4 × 3^2 × 5^2


6. (i) 2000 (ii) 196 (iii) 40 (iv) 768 (v) 0
   (vi) 675 (vii) 144 (viii) 90000


7. (i) – 64 (ii) 24 (iii) 225 (iv) 8000


8. (i) 2.7 × 10^12 > 1.5 × 10^8 (ii) 4 × 10^14 < 3 × 10^17

EXERCISE 13.2

1. (i) 314 (ii) 6^5 (iii) a^5 (iv) 7x+ 2 (v) 5^3 (vi) (10)^5
   (vii) (ab)^4 (viii) 3^12 (ix) 2^8 (x) 8t – 2


2. (i) 33 (ii) 5^3 (iii) 5^5 (iv) 7 × 11^5 (v) 3^0 or 1 (vi) 3
   (vii) 1 (viii) 2 (ix) (2a)^2 (x) a^10 (xi) a^3 b (xii) 2^8
   2. (i) 2 n – 1 → 100 th : 199
   (ii) 3n + 2 → 5 th : 17;
   10 th : 32;
   100 th : 302
   (iii) 4n + 1 → 5 th : 21;
   10 th : 41;
   100 th : 401
   (iv) 7n + 20 → 5 th : 55;
   10 th : 90;
   100 th : 720
   (v) n^2 + 1 → 5 th : 26;
   10 th : 101