Drawing Straight Line Graphs Flashcards

All 6 cards in this deck

What are the steps to draw the graph of a straight line from its equation?
e.g. $y = 2x - 1$ for $x$ from $-1$ to $3$

1. Make a table of values: $x = -1, 0, 1, 2, 3$
2. Work out $y$ for each: $-3, -1, 1, 3, 5$
3. Plot the points and join them with a single straight line, extended over the given range

What is the smallest number of points you should plot when drawing a straight-line graph, and why?

Three — two fix the line and the third checks the points are in line.

What are the steps to find the equation of a line drawn on a grid?
e.g. a line through $(0, 3)$ and $(2, -1)$

1. Gradient from two points on the line: $\frac{-1-3}{2-0} = -2$
2. Read the $y$-intercept: $c = 3$
3. Write $y = mx + c$: $y = -2x + 3$

How do you find where a straight line crosses each axis from its equation?
e.g. $y = 2x - 6$

Put $x = 0$ for the $y$-axis crossing and $y = 0$ for the $x$-axis crossing.
e.g. $(0, -6)$ and $(3, 0)$

What does the graph of $x = 3$ look like?

A vertical line through $(3, 0)$, parallel to the $y$-axis.

True or false? The graph of $y = 4$ is a vertical line.

False. It is a horizontal line through $(0, 4)$; $x = 4$ is the vertical one.