| General equation of a straight line Every first degree equation in x of the form ax + by + c = 0, always represents a straight line. Thus, (ii) x-intercept = (iii) y - intercept = Note : Equation of the x-axis is y = 0 Equation of any horizontal line ( a line parallel to x-axis ) is Equation of the y-axis is x = 0 Equation of any vertical line (a line parallel to y-axis) is x = a , Example Find the slope and intercepts made by the line Solution : ax + by + c º 2x + 5y - 10 = 0 \ a = 2, b = 5 and c = -10 Slope (m) = x-intercept = Or Put y = 0 in 2x + 5y - 10 = 0, then 2x = 10 \ x = 5 y-intercept = Or Put x = 0 in 2x + 5y - 10 = 0, then 5y = 10 \ y = 2 Example Point P (a, 2) lies on the graph of x - 4 = 0. Find a. Solution : Since point p (a, 2) lies on the graph of x - 4 = 0, its co-ordinates satisfy x - 4 = 0, its co-ordinates satisfy x - 4 = 0 i.e. putting x = a we get a - 4 = 0 \ a = 4
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8.1 Definition |
