Drawing-Graphs-From-Tables Edexcel Foundation

Drawing graphs using a table

How do I draw a graph using a table of values?

• To create a table of values

  • substitute different x-values into the equation

  • This gives the y-values

• To plot the points

  • Use the x  and y-values to mark crosses on the grid at the coordinates (x , y )

  • Each point is expected to be plotted to an accuracy within half of the smallest square on the grid

• Draw a single smooth freehand curve 

  • Go through all the plotted points

  • Make it the shape you would expect

    • For example, quadratic curves have a vertical line of symmetry

  • Do not use a ruler for curves!

Which numbers should I be careful with?

• For quadratic graphs, be careful substituting in negative numbers 

• Always put brackets around them and use BIDMAS

  • For example, x = -3 in y = –x² + 8x 

    • becomes y = -(-3)² + 8(-3)

    • which simplifies to -9 – 24

    • so y  = – 33

• For reciprocal graphs like , do not include x  = 0

  • You cannot divide by zero

    • You get an error on your calculator

  • There is no value at x = 0 

    • The L-shaped branches can’t cross the y-axis

  • An example is given below with