Chapter I : Linear Equations in two variables in two variables

Example – 21. Aftab tells his daughter, “Seven years ago, I was seven times as old as you were then . Also, three years from now, I shall be three times as old as you will be.” Represent this situation algebraically and graphically.

Solution :- Let the present age of Aftab be x and that of his daughter y.

7 years ago, age of Aftab = x - 7 and age of his daughter = y - 7.

According to question,        x - 7 = 7(y - 7)

Or,              x - 7y + 42 = 0   ---   ---   ---   ---   (1)

After 3 years, age of Aftab = x + 3 and age of his daughter = y + 3.

According to question,         x + 3 = 3(y + 3)

Or,               x – 3y – 6 = 0  ---   ---   ---   ---   (2)

The above statement represented algebraically are (1) and (2).

To represent graphically, draw the graph. The points are given below:

For equation (1) :-&

x 0 7 14
y 6 7 8

For equation (2) :-

x 6 9 12
y 0 1 2
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Subjects Maths (Part-1) by Mr. M. P. Keshari
Chapter 1 Linear Equations in Two Variables
Chapter 2 HCF and LCM
Chapter 3 Rational Expression
Chapter 4 Quadratic Equations
Chapter 5 Arithmetic Progressions
Chapter 6 Instalments
Chapter 7 Income Tax
Chapter 8 Similar Triangles