Show that the solution set of the following linear constraints is empty:
x - 2y ≥ 0, 2x - y≤ - 2, x ≥ 0 and y ≥ 0
Consider the inequation x - 2y ≥ 0:
⇒x ≥ 2y
⇒y≤
consider the equation y = . This equation’s graph is a straight line passing through origin.
Now consider the inequality y≤
Here we need the y value less than or equal to
⇒ the required region is below origin.
Therefore the graph of the inequation y≤ is fig.10a
Fig 10a
Consider the inequation 2x - y≤ - 2 :
⇒y ≥ 2x + 2
Consider the equation y = 2x + 2
Finding points on the coordinate axes:
If x = 0, the y value is 2 i.e, y = 2
⇒ the point on Y axis is A(0,2)
If y = 0, 0 = 2x + 2
⇒x = - 1
The point on X axis is B( - 1,0)
Now consider the inequality y ≥ 2x + 2
Here we need the y value greater than or equal to 2x + 2
⇒ the required region is above point A.
Therefore the graph of the inequation y ≥ 2x + 2 is fig. 10b
Fig 10b
y ≥ 0 is the region above X - axis
x ≥ 0 is the region right side of Y - axis
Combining the above results, we’ll get
As they is no common area of intersection , there is no solution for the given set of simultaneous inequations.