1. Lines in the Plane
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Recall the definitions of the form of equations.
(a) iii
(b) i
(c) v
(d) ii
(e) iv
Form of Equations | Definition |
---|---|
(i) vertical line | A line with undefined slope is vertical. It always intersect the x-axis at a point a and expressed as x=a. |
(ii) slope-intercept form | The slope-intercept form of the equation of the line that has a slope of m and y-intercept of (0,b) is y=mx+b. |
(iii) general form | The general form of the equation of a line is Ax+By+C=0, where A, B, and C are constants. |
(iv) point-slope form | The point-slope form of the equation of the line that passes through the point (x_1,y_1) and has a slope of m is y-y_1 = m(x-x_1). |
(v) horizontal line | A line with zero slope is horizontal. It always intersect the y-axis at a point b and expressed as y=b. |
We can now match each equation with its form.
Equations | Form of Equations |
---|---|
(a) Ax+By+C=0 | (iii) general form |
(b) x=a | (i) vertical line |
(c) y=b | (v) horizontal line |
(d) y=mx+b | (ii) slope-intercept form |
(e) y-y_1 = m(x-x_1) | (iv) point-slope form |