For periods A and D, tips on formulas and tables

Tips:

If you are figuring out a formula from a table plug in other values from the table to see it works. For example say you have x values = 1,2,3,4 and corresponding y values = 2,4,6,8. Let's say you look at the first x and y value and see x = 1 and y = 2 and conclude:

y = x + 1,

You would then check this with the next x and y values, x = 2, y = 4 and see that x + 1 only equals 3 and therefore y = x + 1 is an incorrect formula for this table. You could then come up with the formula y = 2x, check this formula with all values, see that it works with all values and conclude this is the correct formula. NOTE: always check your answers.

Another tip:
If the value is being increased, as in the above example from x to y, you know you need to either add something to the x variable (add a number greater than zero) or multiply the x variable (by a number greater than 1).

If the value is being decreased, then you need to know the variable being decreased must either be subtracted from (subtract a number greater than zero) or divided by (a number greater than 1).