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31. Mathematical Reasoning
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Q5 of 134 Page 31

Show that the following statement is true

“The integer n is even if and only if n2 is even”

Let the statements,


p: Integer n is even


q: If n2 is even


Let p be true.


Then


Let n = 2k


Squaring both the sides, we get,


n2 = 4k2


n2 = 2.2k2


Therefore, n2 is an even number.


So, q is true when p is true.


Hence, the statement is true.


More from this chapter

All 134 →
3

Show that the statement

p : “If x is a real number such that x3 + x = 0, then x is 0” is true by


(i) Direct method


(ii) method of contrapositive


(iii) method of contradiction

4

Show that the following statement is true by the method of the contrapositive

p : “If x is an integer and x2 is odd, then x is also odd.”

6

By giving a counter example, show that the following statement is not true.

p : “If all the angles of a triangle are equal, then the triangle is an obtuse angled triangle.”

7

Which of the following statements are true and which are false? In each case give a valid reason for saying so

(i) p : Each radius of a circle is a chord of the circle.


(ii) q : The centre of a circle bisect each chord of the circle.


(iii) r : Circle is a particular case of an ellipse.


(iv) s : If x and y are integers such that x > y, then – x < - y.


(v) is a rational number.

Questions · 134
31. Mathematical Reasoning
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