In which quadrant will the point $\left( {2, - 1} \right)$ lie?
(A) I
(B) II
(C) III
(D) IV

Hint: In this question, we are given x,y coordinates of a point and we need to find the quadrant in which the point lies. For this, we will first understand the type of points every quadrant has and then compare them with the given point to find the required point.

Complete step by step answer:
We need to find the quadrant in which $\left( {2, - 1} \right)$ lies. For this, let us first understand the coordinate system.
In a Cartesian plane, we have x axis and y axis which cut each other to form four quadrants.

Positive x coordinate lies on the right side of the y axis and the negative x coordinate lies on the left side of the y axis. Positive y coordinate lies above the x axis and the negative y coordinate lies below the x axis.
Then we can see that, in the first quadrant,
We have positive x coordinate and positive y coordinates. Therefore, in the first quadrant, points are of the form \[\left( {x,y} \right)\].
In the second quadrant,
We have positive y coordinate and negative x coordinate. Therefore, in the second quadrant, points are of the form \[\left( { - x,y} \right)\].
In the third quadrant, we have negative x coordinate and negative y coordinate. Therefore, in the third quadrant, points are of the form \[\left( { - x, - y} \right)\].
In the fourth quadrant,
We have positive x coordinate and negative y coordinate. Therefore, in the fourth quadrant, points are of the form \[\left( {x, - y} \right)\].
Now, we are given the point as $\left( {2, - 1} \right)$. As we can see it is in the form \[\left( {x, - y} \right)\]. Since the fourth quadrant has points of the form \[\left( {x, - y} \right)\] therefore our point $\left( {2, - 1} \right)$ lies in the fourth quadrant.
Therefore, the correct answer is “Option D”.

Note: Students should note that, x coordinate is always written first and y coordinate is written next. x coordinate is also called as abscissa and y coordinate is also called as ordinate. Students often make mistakes in naming quadrants in the Cartesian plane. Quadrant means start from the top right corner and move in an anticlockwise direction.