Page 167 - Mathematics

Chapter summary

1. The xy-coordinate plane or xy-plane is made up of two number lines
intersecting at right angles.

2. The horizontal axis is called the x-axis. Tanzania Institute of Education

3. The vertical axis is called the y-axis.
4. The point at which the two axes intersect is called the origin.

5. The two axes divide the xy-plane into four equal parts called quadrants.

6. Each coordinate point in the coordinate plane has two numbers called
coordinates written as an ordered pair (x, y).
7. The formula for calculating the gradient or slope is
change in coordinatesy
m = .
change in coordinatesx
8. A vertical line has an undefined gradient and is parallel to the y-axis.

9. A horizontal line has a gradient whose value is 0 and is parallel to the
x-axis.
10. The equation of a line can be written in the form y = mx c+ , where m
is the gradient and c is a constant.

11. The general equation of a line has the form ax by c+ += 0.

12. Graphs of linear simultaneous equations intersect at a common point
whose coordinates give the solution of the equation.
13. Linear simultaneous equations in two unknowns have solution of an
ordered pair (x, y).

Revision exercise 6

1. Find the equation and y-intercept of each line passing through the
following pair of points.

(a) (4, 4), ( 3, 2)− (d) ( 2,− − 2), (4, 1)
 4   3  Mathematics Form One
(b) ( 7, 2), (2, 7)− (e)   7 ,6 ,   2 ,6  


 5  1 
(c)  , 2 , 6,  (f) ( 155, 541) (541, 155)− −

 6  6 

161

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Mathematics form 1.indd 161