Which of the following pairs of linear equations are consistent/inconsistent? If consistent, obtain the solution graphically.
(i) x + y = 5, 2x + 2y = 10
(ii) x-y – 8, 3x – 3y = 16
(iii) 2x + y – 6 = 0, 4x – 2y – 4 = 0
(iv) 2x – 2y – 2 = 0, 4x – 4y – 5 = 0
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Answer:
The Second, Fourth one is inconsistent:
Explanation:
(i) x+y=5 ...(i)
2x+2y=10 ...(ii)
On rearranging the variables in (i)
You get y=5-x
So the(x,y) pair will be
x 0 3
y 5 2
Plot (0,5) and (3,5) on graph and join them to get equation x+y=5.
2x+2y=10
⇒2y=(10−2x)
⇒y= (10−2x)/2 =5−x ...(iii)
Next Pair
x 5 2
y 0 3
Plot (5,0) and (5,3) on graph and join them to get equation 2x+2y=10
So, the equation is consistent and has infinitely many solution
(iii)2x+y−6=0
4x−2y−4=0
2x+y=6 ....(i)
4x−2y=4 ...(ii)
For equation (i),
2x+y=6⇒y=6−2x
x 0 3
y 6 0
Plot point (0,6) and (3,0) on a graph and join then to get equation 3x+y=6
For equation (ii), 4x−2y=4⇒
2y=4x−4
y=(4x-4)/2
x 1 0
y 0 −2
Plot point (1,0) and (0,−2) on a graph and join them to get equation 4x−2y=0
x=2,y=2 is the solution of the given pairs of equation . So. solution is consistent.
Hope This Helps........
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