Drawing-Straight-Line-Graphs Wjec-Eduqas Foundation

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Exam code:C300

Drawing linear graphs

How do I draw a straight line from a table of values?

You may be given a table of values with no equation
Use the x and y values to form a point with coordinates (x , y )
- Then plot these points
- Use a ruler to draw a straight line through them
  - All points should lie on the line
For example
- The points below are (-3, 0), (-2, 2), … etc

$x$	-3	-2	-1	0	1	2	3
$y$	0	2	4	6	8	10	12

How do I draw a straight line using y = mx + c?

Use the equation to create your own table of values
- Choose points that are spread out across the axes given
For example, plot y = 2x + 1 on axes from x = 0 to x = 10
- Substitute in x = 0, x = 5 and x = 10 to get y coordinates
  - Then plot those points

$x$	0	5	10
$y$	1	11	21

How do I draw a straight line without using a table of values?

Start at the y-intercept, c
Then, for every 1 unit to the right, go up m units
- m is the gradient
- If m is negative, go down
- If m is a fraction, remember that gradient is change in y divided by change in x
  - A gradient of $a over b$ would be $a$ units up for every $b$ units right
This creates a sequence of points which you can then join up
- Be careful of counting squares if axes have different scales
  - 1 unit might not be 1 square

Examiner Tips and Tricks

Always plot at least 3 points (just in case one of your end points is wrong!)

Worked Example

On the same set of axes, draw the graphs of $y equals 3 x minus 1$ and <img alt=”y equals negative 3 over 5 x plus 3″ data-mathml='<math ><semantics><mrow><mi>y</mi><mo>=</mo><mo>-</mo><mfrac><mn>3</mn><mn>5</mn></mfrac><mi>x</mi><mo>+</mo><mn>3</mn></mrow><annotation encoding=”application/vnd.wiris.mtweb-params+json”>{“language”:”en”,”fontFamily”:”Times New Roman”,”fontSize”:”18″,”autoformat”:true}</annotation></semantics></math>’ height=”47″ role=”math” src=”data:image/svg+xml;charset=utf8,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20xmlns%3Awrs%3D%22http%3A%2F%2Fwww.wiris.com%2Fxml%2Fmathml-extension%22%20height%3D%2247%22%20width%3D%2298%22%20wrs%3Abaseline%3D%2230%22%3E%3C!–MathML%3A%20%3Cmath%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi%3Ey%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmo%3E-%3C%2Fmo%3E%3Cmfrac%3E%3Cmn%3E3%3C%2Fmn%3E%3Cmn%3E5%3C%2Fmn%3E%3C%2Fmfrac%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%2B%3C%2Fmo%3E%3Cmn%3E3%3C%2Fmn%3E%3C%2Fmath%3E–%3E%3Cdefs%3E%3Cstyle%20type%3D%22text%2Fcss%22%3E%40font-face%7Bfont-family%3A’math190bc3972c7934354efb2af01e7’%3Bsrc%3Aurl(data%3Afont%2Ftruetype%3Bcharset%3Dutf-8%3Bbase64%2CAAEAAAAMAIAAAwBAT1MvMi7iBBMAAADMAAAATmNtYXDEvmKUAAABHAAAAERjdnQgDVUNBwAAAWAAAAA6Z2x5ZoPi2VsAAAGcAAABdWhlYWQQC2qxAAADFAAAADZoaGVhCGsXSAAAA0wAAAAkaG10eE2rRkcAAANwAAAAEGxvY2EAHTwYAAADgAAAABRtYXhwBT0FPgAAA5QAAAAgbmFtZaBxlY4AAAO0AAABn3Bvc3QB9wD6AAAFVAAAACBwcmVwa1uragAABXQAAAAUAAADSwGQAAUAAAQABAAAAAAABAAEAAAAAAAAAQEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACAgICAAAAAg1UADev96AAAD6ACWAAAAAAACAAEAAQAAABQAAwABAAAAFAAEADAAAAAIAAgAAgAAACsAPSIS%2F%2F8AAAArAD0iEv%2F%2F%2F9b%2Fxd3xAAEAAAAAAAAAAAAAAVQDLACAAQAAVgAqAlgCHgEOASwCLABaAYACgACgANQAgAAAAAAAAAArAFUAgACrANUBAAErAAcAAAACAFUAAAMAA6sAAwAHAAAzESERJSERIVUCq%2F2rAgD%2BAAOr%2FFVVAwAAAQCAAFUC1QKrAAsASQEYsgwBARQTELEAA%2FaxAQT1sAo8sQMF9bAIPLEFBPWwBjyxDQPmALEAABMQsQEG5LEBARMQsAU8sQME5bELBfWwBzyxCQTlMTATIREzESEVIREjESGAAQBVAQD%2FAFX%2FAAGrAQD%2FAFb%2FAAEAAAIAgADrAtUCFQADAAcAZRgBsAgQsAbUsAYQsAXUsAgQsAHUsAEQsADUsAYQsAc8sAUQsAQ8sAEQsAI8sAAQsAM8ALAIELAG1LAGELAH1LAHELAB1LABELAC1LAGELAFPLAHELAEPLABELAAPLACELADPDEwEyE1IR0BITWAAlX9qwJVAcBV1VVVAAEAgAFVAtUBqwADADAYAbAEELEAA%2FawAzyxAgf1sAE8sQUD5gCxAAATELEABuWxAAETELABPLEDBfWwAjwTIRUhgAJV%2FasBq1YAAAAAAQAAAAEAANV4zkFfDzz1AAMEAP%2F%2F%2F%2F%2FWOhNz%2F%2F%2F%2F%2F9Y6E3MAAP8gBIADqwAAAAoAAgABAAAAAAABAAAD6P9qAAAXcAAA%2F7YEgAABAAAAAAAAAAAAAAAAAAAABANSAFUDVgCAA1YAgANWAIAAAAAAAAAAKAAAAKEAAAErAAABdQABAAAABABeAAUAAAAAAAIAgAQAAAAAAAQAAN4AAAAAAAAAFQECAAAAAAAAAAEAEgAAAAAAAAAAAAIADgASAAAAAAAAAAMAMAAgAAAAAAAAAAQAEgBQAAAAAAAAAAUAFgBiAAAAAAAAAAYACQB4AAAAAAAAAAgAHACBAAEAAAAAAAEAEgAAAAEAAAAAAAIADgASAAEAAAAAAAMAMAAgAAEAAAAAAAQAEgBQAAEAAAAAAAUAFgBiAAEAAAAAAAYACQB4AAEAAAAAAAgAHACBAAMAAQQJAAEAEgAAAAMAAQQJAAIADgASAAMA

Maths Gcse Wjec-Eduqas Foundation