ExamGOAL
Books
15
Subjective

Prove by direct method that for any real number $x, y$ if $x=y$, then $x^2=y^2$.

Explanation

Let $p: x=y, \quad x, y \in R$

On squaring both sides,

$$\begin{gathered} x^2=y^2: q \quad\text{[say]}\\ p \Rightarrow q \end{gathered}$$

Hence, we have the result.

16
Subjective

Using contrapositive method prove that, if $n^2$ is an even integer, then $n$ is also an even integer.

Explanation

Let $p: n^2$ is an even integer.

$q: n$ is also an even integer.

Let $\sim p$ is true i.e., $n$ is not an even integer.

$\Rightarrow n^2$ is not an even integer. $\quad$ [since, square of an odd integer is odd]

$\Rightarrow \sim p$ is true.

Therefore, $\sim q$ is true $\Rightarrow \sim p$ is true.

Hence proved.

17
MCQ (Single Correct Answer)

Which of the following is a statement?

A
$x$ is a real number
B
Switch off the fan
C
6 is a natural number
D
Let me go
18
MCQ (Single Correct Answer)

Which of the following is not a statement.

A
Smoking is injurious to health
B
$2+2=4$
C
2 is the only even prime number
D
Come here
19
MCQ (Single Correct Answer)

The connective in the statement ' $2+7>9$ or $2+7<9$ ' is

A
and
B
or
C
$>$
D
$<$