Coordinates and Linear Functions (Consolidation Que7-12)

Common mistakes

***2cm represent 10 mini square, 1cm represent 5 mini square,

***Label number every 2cm 10 mini squ, 1 BIG squ

  1. Never write scale (x axis: 2cm to 1 unit, y axis: 1cm to 1 unit)
  2. Use odd scale (x axis: 1cm to 3 unit or 1cm to 1.5 unit)
  3. If question says “From GRAPH” show that when y=2, x=4… DON”T use substitution method to solve on graph paper, DO show dotted lines on graph to find answer
  4. If question ask you to DRAW Line, always start with a 2 row 3 column table, x value on top, y value below, ONLY 3 points are needed
  5. How to CHOOSE X value for table?

If y=4x/5+3, choose x: 0,5,10 since these values will give a nice integer for y

Ify=4x+5, and x is between -5 to 10, choose x: -5,0,10, since these values will give the min y and max y

LASTLY MOST important:

Check again after

  1. rearranging equation into nice “y=mx+c” format
  2. after filling in x and y table
  3. after plotting in the 3 points
  4. after finding coordinates to calculate gradient

gradient= (y1-y2)/(x1-x2)

Question 9) redo: without plotting, draw another graph of y=2x+1 on the same graph where you drew y=2x-3

gradient remain the same –> parallel lines

but the whole graph shift up, y shift upwards by +4

y intercept change from -3 to +1,

*** x remains UNCHANGEd… (0,-3) –> (0,1)