- ab ≠ 0, a < 0 && b < 0 or a > 0 && b > 0
- Data Interpretation
**Average speed a → b and b → a**Average speed =`total distance / total time`

1st let any distance from point A to point B Get total time using`s = vt`

rule Get the time for the given one Get the other time from the total time and using that get the speed for the 2nd one- we cant assume parallel or right angle if not given
- In QC, check x
**int**or**float** - could be means it can be for any numbers
- We cant cross out from both sides of the eqn unless it is not told that they are greater than 0
- divided by X not by Y, -
**Check for both by X and not by** - 0.2 * 0.2 = 0.04, not 0.4 0.4 * 0.04 = 0.016 not 0.16 or 1.6
- Square root always + and -,

$$ p^2/q^2 = 4 $$

$$ p = +- 2 $$

- If we get 2 answers, do check by replacing on the main eqn if both are valid or not
- The number of multiples between a^2 and a^5 = (a^5 - a^2)/a - 1
- how much increase/decrease or how much after if increase/decrease plus or minus from the previous value
- fraction square make the number less always
- use 30-60-90 and 45-45-90 more
- Integer factors means divisors, prime factors means prime divisors