Algebra
Coordinate geometry
Read and plot points on the coordinate plane and name the quadrant they lie in.
Take two number lines and lay one across the other so they cross at zero. The one going across is the x-axis, the one going up is the y-axis, and the crossing point is the origin. Now any point anywhere on the flat page can be named by exactly two numbers.
Along the corridor, then up the stairs
A pair like (3, 5) is always read x first, y second: go 3 along, then 5 up. Swapping them gives a completely different point, so the order is not a detail.
Worked example
Where is the point (3, -2)?
The first number is 3, so start at the origin and go 3 to the right.
A positive x-coordinate means right; a negative one would mean left.
Have a play
The two axes cut the page into four quarters. Find out what each one is called — all four, in any order, nothing to get right.
Tap any part of the picture.
Try it together
Which quadrant is the point (-5, 4) in?
You do not need to draw anything. The two signs alone tell you the answer.
1.Look at the x-coordinate, -5. Is it positive or negative? Type positive or negative.
Points on an axis belong to no quadrant
(5, 0) sits on the x-axis and (0, 5) sits on the y-axis. A quadrant is the space between two axes, so a point sitting exactly on one is not inside any of them.
Have a go
Have a go on your own: which quadrant is (7, -3) in?
Ready to practise?
Eight questions on what you have just read. Nothing is timed, and you can play as many times as you like.