# NCERT Class 9 Maths Formula CBSE Board Sample Problems Part 4

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## 4. Linear Equations in Two Variables

An equation of the form ax + by + c = O, where a, b and c are real numbers, such that a and b are not both zero, is called a linear equation in two variables

Important points to Note

S.no | Points |

1 | A linear equation in two variable has infinite solutions |

2 | The graph of every linear equation in two variable is a straight line |

3 | x = O is the equation of the y-axis and y = O is the equation of the x-axis |

4 | The graph x=a is a line parallel to y -axis. |

5 | The graph y=b is a line parallel to x -axis |

6 | An equation of the type y = mx represents a line passing through the origin. |

7 | Every point on the graph of a linear equation in two variables is a solution of the linear equation. Moreover, every solution of the linear equation is a point on the graph |