Step by step
The question
Question: graph and remove t from x = −t, y = t² + 1.
1 Make a table
Each t gives a point.
Start with t = −2.
x is −(−2): 2.
y is (−2)² + 1: 5.
Minus times minus is plus.
Put the t's in a table.
Work out x for each t,
and y for each t.
2 Plot the points
Draw the grid.
Put each (x, y) on the grid.
3 Join in order of t
Join the points in order: t = −2, then −1, and on.
The arrows show the way t grows.
t can go on, so the curve goes on.
4 Remove t
−t is x.
So t = −x: change the sign.
Put t into y = t² + 1, with its bracket: y = (−x)² + 1.
Careful!
The whole of −x is squared, not only the last number.
So it keeps its bracket.
A minus squared is plus: y = x² + 1.
5 Check
Let's check with a point from the table: t = 2 gave (−2, 5).
Put x = −2 into the answer.
We get y = 5, the same as the table.
Right!
Let's look back.
First: make a table.
Then: plot the points.
Then: join in order of t.
Then: remove t.
Last: check.