Gujarat Board Textbook Solutions Class 9 Maths Chapter 1 Number Systems Ex 1.2

Gujarat Board Textbook Solutions Class 9 Maths Chapter 1 Number Systems Ex 1.2

GSEB Solutions Class 9 Maths Chapter 1 Number Systems Ex 1.2

Question 1.
State whether the following statements are true or false. Justify your answers.
(i) Every irrational number is a real number.
(ii) Every point on the number line is of the form m, where m is a natural number.
(iii) Every real number is an irrational number.
Solution:
(i) True, because collection (set) of a real number consist rational and irrational number.

(iii) False, because a real number can be either a rational number or irrational number. For example, 3 is a real number but not an irrational number.

Question 2.
Are the square roots of all positive integers irrational? If not, give an example of the square root of a number that is a rational number.
Solution:
No. For example, 4 = 2 and 9 = 3 are rational number, but not irrational.

Question 3.
Show how 5 can be represented on the number line.
Solution:
Consider a unit square OABC with each side unit in length, then by Pythagoras theorem
OB2 = OA2 + AB2
OB2 = 12 + 12 = 1 + 1
OB = 2 units
Then construct BD = 1 unit perpendicular to OB.
Then again by Pythagoras theorem in ΔODE

With centre O and radius equal to OF draw an arc which intersects the number line at the point P, then

Question 4.
(Classroom activity) (Constructing the square root spiral)
Solution:
Let us take a large sheet of paper and construct the square root spiral in the following position. Start with a point O and draw a line segment OP1 of unit length. Draw a line segment P1P2 perpendicular to OP1 of unit length. Now draw a line segment P2P3 perpendicular to OP2. Then draw a line segment P3P4 perpendicular to OP3. Continuing in this manner, we can get the line segment Pn-1 Pn by drawing a line segment of unit length perpendicular to OPn-1 In this manner, we will have created the points P2, P3, …., Pn …… and joined them to create a beautiful spiral depicting 2, 3, 4, ……….

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