x+y=5, 2x+2y=10 chapter-3 exercise 3.1-Q4 (i)-pair of linear equations in two variables

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 4. Which of the following pairs of linear equations are consistent/inconsistent? If consistent, obtain the solution graphically:

  (i) x+y=5, 2x+2y=10

    x+y–5=0 ----------(1)

    2x+2y–10=0 ---------(2)

    a1/a2 = 1/2,  b1/b2 = 1/2 

    c1/c2 = -5/-10 = ½

  from the above we can say

     a1/a2 = b1/b2 = c1/c2

   above formula belongs to coincident

   coincident lines are consistent

    Graphically Solving

   x + y – 5 =0

   y = 5- x


Table 1
x 1 2 3
y=5-x    4    3   2
(x,y)  (1,4)  (2,3)  (3,2)
Y = 5-x
5-1=4
5-2=3
5-3=2

2x + 2y – 10 = 0
2y = 10 – 2x
y = (10-2x)/2


Table 
x 1 2 3
y=(10-2x)/2    4     3   2
(x,y) (1,4)   (2,3)   (3,2)

Y = (10-2x)/2
   = (10-2(1))/2 = 10-2/2 = 8/2 = 4
Y = (10-2x)/2
   = (10-2(2))/2 = 10-4/2 = 6/2 = 3
Y = (10-2x)/2
   = (10-2(3))/2 = 10-6/2 = 4/2 = 2

Post details: CBSE Class 10 Maths NCERT 10 Maths
Chapter Name : Pair of Linear Equations in Two Variables
Exercise : 3.1
Question Number : 4 (i)

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