Question

How do you write an equation of a line given point (0,-4) and (5,-4)?

Answer 1

`y+4=0.`

Explanation:

If we notice that the Y-co-ords. of given two pts. thro. which line passes are same, the eqn. can immediately be written as `: y=-4, or, y+4=0`

This behaviour of pts. on a line occur, when and only when, the line is Horizontal , i.e., line `||` to the X-axis.

Otherwise, we may use the formula for the eqn. of a line passing thro. pts. `(x_1,y_1) and (x_2,y_2)` given by, `: (y-y_1)/(x-x_1)=(y_2-y_1)/(x_2-x_1)` to give,

`(y+4)/(x-0)=(-4+4)/(5-0)=0 rArr y+4=0.`

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