NCTB Class 7 Math Chapter One Exercise 1.2 Solution

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 a2.

Therefore, 20 a2.= 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 = 10x2 Rs.

Therefore, 10x2 = 6250

=> x2 = 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 – x2 = 37

=> x2+ 2x+1- x2 = 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 – x2

= x2+ 2x+1- x2

= 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.

Updated: December 11, 2020 — 8:34 am

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