NCERT Class 9 Solutions: Linear Equation in Two Variable (Chapter 4) Exercise 4.2 – Part 2

Following figure explains how to find x and y intercepts.

Give figure of finding a and y intercepts,equation is x-2y=4,then meet the (x,y)=(4,-2)

Give Figure of Finding a and Y Intercepts

Give figure of finding a and y intercepts,equation is x-2y=4,then meet the (x,y)=(4,-2)

Q-3 Check which of the following are solutions of the equation x2y=4 and which are not:

  1. (0,2)

  2. ( 2,0)

  3. (4,0)

  4. (2,42)

  5. (1,1)

Solution:

  • Given the equation x2y=4

  • A point is a solution to this equation, if it lies on the graph of the equation. That is the equation is satisfied when we put in corresponding coordinates and L.H.S = R.H.S

  1. (0,2)

    Putting x=0 and y=2 in the L.H.S of the given equation,

    x2y=02×2=44

    L.H.S R.H.S

    Therefore, (0,2) is not a solution of this equation.

  2. (2,0)

    Putting x=2 and y=0 in the L.H.S of the given equation,

    22×0=24

    L.H.S R.H.S

    Therefore, (2,0) is not a solution of this equation.

  3. (4,0)

    Putting x=4 and y=0 in the L.H.S of the given equation,

    x2y=42(0)=4= R.H.S

    Therefore, (4,0) a solution of this equation.

  4. (2,42)

    Putting x=2 and y=42 in the L.H.S of the given equation,

    x2y=282=724

    L.H.S R.H.S

    Therefore, (2,42) is not a solution of this equation.

  5. (1,1)

    Putting x=1 and y=1 in the L.H.S of the given equation,

    x2y=124

    L.H.S R.H.S

    Therefore, (1,1) is not a solution of this equation.

Q-4 Find the value of k, if x=2,y=1 is a solution of the equation 2x+3y=k.

Solution:

  • Give the equation of 2x+3y=k.

  • Since x=2 and y=1 is a solution to the equation, it must satisfy the equation

    Thus, 2(2)+3(1)=k 4+3=k

  • So, the value of k is 7

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