NCTB Class 7 Math Chapter One Exercise 1.2 Solution by Math Expert. Bangladesh Board Class 7 Math Solution Chapter 1”Rational & Irrational Numbers” Exercise 1.2 Solution.

Board |
NCTB |

Class |
7 |

Subject |
Math |

Chapter |
1 |

Chapter Name |
”Rational & Irrational Numbers” |

Exercise |
1.2 Solution |

**Exercise:- 1.2**

**(3) A rational number is —**

**Solution:- **(d) (i), (ii), (iii) are correct.

**The difference of squares of two consecutive numbers is 19.**

**Answer to question no. 4 and 5 following the information.**

**(4) If one number is 10, what is the other number?**

**Solution:- **Two consecutive number is 9, 10 other number is = (c) 9.

**(5) What is the sum total of squares of the two numbers?**

**Solution:- **(10)^{2}+ (9)^{2} = 100+ 81

(c) = 181.

**(6) Which of the following is the square root of 0.01?**

**Solution:-** √ 0.01= 0.1 (b)

**(7) If the digit in unit place of a number is either 2 or 8, the digit in unit place of its square will be — **

**Solution:- **(c) 6.

**(8) By which number the multiplication or division of 3×7 x5x 7×3 will be perfect square number?**

** Solution:- **3×7 x5x 7×3

= (3×3) x (7×7) x 5

Therefore, the number is (b) 5 (answer).

**(9) Which one of the irrational number?**

**Solution:- **The irrational number is = (a) √2.

**(10) (a) How much money did he spend to buy the plants?**

**Solution:-** Total money speed = (12×595)= 7140 Rs (Taka).

**(17) Each member of a cooperative society subscribes 20 times the number ****of the members in Takas. The total amount raised being TK.20480, find the number of members of the society.**

**Solution:- **Let, the number of member is a

Therefore, 1 —- a x 20

Therefore, a —- a x a x 20

= 20 a^{2}.

Therefore, 20 a^{2}.= 20480 (Total amount).

=> a2 = 20480/20

=> 1024

=> a = √ 1024 = 32

Therefore, The number of member of society is 32.

**(20) Labours were employed to reap paddy from a paddy field. The daily wage of each labour is 10 times of their numbers. If the total daily wage is TK.6250, find the number of the labours. **

**Solution:- **Let, the number of labour x.

Therefore, wages = xX10 = 10x Rs.

Therefore, = x X 10x = 10x^{2} Rs.

Therefore, 10x^{2} = 6250

=> x^{2} = 625

=> x=25

Therefore, The number of labour is 25.

**(21) The difference of squares of two consecutive number is 37. Find the two number.**

**Solution:-** Let, the number are x & x+1

Therefore, Square of numbers = and (x+1)^{2}

Therefore, (x+1)^{2 }– x^{2 }= 37

=> x^{2}+ 2x+1- x^{2} = 37

=> 2x +1= 37

=> 2x = 37-1

=> x = 36/2

= 18

Number are 18, 19 (Answer) and another number is = (18+1) = 19.

**(22) Solution:-**

Let, the number, x & x+1

Therefore Difference of square of the number

= (x+1)^{2 }– x^{2}

= x^{2}+ 2x+1- x^{2}

= 2x+1

Therefore, x=2 ; 2×2+1= 5

X=3 ; 2x3x1= 7

X=4; 2×4+1 = 9 (Square number)

Therefore, One number is 4 and another number (4+1) = 5.

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