Q1 of 18 Page 898

Which of the following sentences are statements? In case of a statement mention whether it is true or false.

(i) The sun is a star.


(ii) √7 is an irrational number.


(iii) The sum of 5 and 6 is less than 10.


(iv) Go to your class.


(v) Ice is always cold.


(vi) Have you ever seen the Red Fort?


(vii) Every relation is a function.


(viii) The sum of any two sides of a triangle is always greater than the third side.


(ix) May God bless you!


(i) The sun is a star is a statement. It is a scientifically proven fact that the sun is a star and, therefore this sentence is always true. Hence it is a statement, and it is true.


Note: A sentence is called a mathematically acceptable statement if it is either true or false but not both.


(ii) √7 is an irrational number. An irrational number is any number which cannot be expressed as a fraction of two integers. √7 cannot be expressed as a fraction of two integers, so √7 is an irrational number; therefore the sentence is always true. Hence it is a statement, and it is true.


Note: A sentence is called a mathematically acceptable statement if it is either true or false but not both.


(iii) The sentence is true because the sum of 5 and 6 is not less than 10. Sum of 5 and 6 is 11, which is not less than 10. Hence it is a statement. The statement is true.


Note: A sentence is called a mathematically acceptable statement if it is either true or false but not both.


(iv) This sentence ‘Go to your class’ is an order. Hence it is not a statement.


Note: A sentence which is in the form of an order, exclamation and question is not a statement.


(v) Ice is always cold is a statement. It is scientifically proven the fact that ice is always cold and, therefore the sentence is always true.


Hence it is a statement, and it is true.


Note: A sentence is called a mathematically acceptable statement if it is either true or false but not both.


(vi) The sentence ‘Have you ever seen the Red Fort? Is a question, hence it is not a statement.


Note: A sentence which is in the form of an order, exclamation and question is not a statement.


(vii) The sentence ‘Every relation is a function’ is a statement. There are relations which are not functions. Therefore the sentence is false. Hence it is a statement, and it is false.


Note: A sentence is called a mathematically acceptable statement if it is either true or false but not both.


(viii) The sentence ‘The sum of any two sides of a triangle is always greater than the third side’ is a statement. Because the sum of any two sides of the triangle is always greater than the third side. Hence the statement is true.


(ix) The sentence ‘May God bless you!’ is an exclamation. Hence it is not a statement.


Note: A sentence which is in the form of an order, exclamation and question is not a statement.


More from this chapter

All 18 →
2

Which of the following sentences are statements? In case of a statement, mention whether it is true or false.

(i) Paris is in France.


(ii) Each prime number has exactly two factors.


(iii) The equation x2 + 5|x| + 6 = 0 has no real roots.


(iv) (2 + √3) is a complex number.


(v) Is 6 a positive integer?


(vi) The product of -3 and -2 is -6.


(vii) The angles opposite the equal sides of an isosceles triangle are equal.


(viii) Oh! It is too hot.


(ix) Monika is a beautiful girl.


(x) Every quadratic equation has at least one real root.


3

Which of the following statements are true and which are false? In each case give a valid reason for your answer.

(i) p: √11 is an irrational number


(ii) q: Circle is a particular case of an ellipse.


(iii) r: Each radius of a circle is a chord of the circle


(iv) S: The center of a circle bisects each chord of the circle


(v) t: If a and b are integers such that a < b, then –a > -b.


(vi) y: The quadratic equation x2 + x + 1 = 0 has no real roots


4

Write the negation of each of the following statements:

(i) Every natural number is greater than 0.


(ii) Both the diagonals of a rectangle are equal.


(iii) The sum of 4 and 5 is 8.


(iv) The number 6 is greater than 4.


(v) Every natural number is an integer.


(vi) The number -5 is a rational number


(vii) All cats scratch.


(viii) There exists a rational number x such that x2 = 3.


(ix) All students study mathematics at the elementary level.


(x) Every student has paid the fees.


(xi) There is some integer k for which 2k = 6.


(xii) None of the students in this class has passed.


1

Split each of the following into simple sentences and determine whether it is true or false.

(i) A line is straight and extends indefinitely in both the directions.


(ii) A point occupies a position, and its location can be determined.


(iii) The sand heats up quickly in the sun and does not cool down fast at night.


(iv) 32 is divisible by 8 and 12.


(v) x = 1 and x = 2 are the roots of the equation x2 – x – 2 = 0.


(vi) 3 is rational, and √3 is irrational.


(vii) All integers are rational numbers, and all rational numbers are not real numbers.


(viii) Lucknow is in Uttar Pradesh, and Kanpur is in Uttarakhand.