Math is not rocket science. Rolf Handke / Pixelio

### Multiplying out of staples

When multiplying the applicable - little mathematically formulated - usually that factor outside the brackets must be multiplied by each value in parentheses.

- It is important to observe the principle of "point before dashes" and the rules for positive and negative numbers. Reminder: "point before dashes" means that the multiplication and division must be calculated before addition and subtraction. The rules for positive and negative numbers are that in the multiplication of two positive numbers, the result is positive, when multiplying two negative numbers, the result is positive, and in the multiplication of a positive and a negative number, the result is negative.
- Taking for example the following formula: a * (b - c), the multiplying quoting the above rules so: from - ac; a is thus multiplied by any number and of (+ a) * (- c) - ac.
- The same applies for the multiplying of two brackets: (a + b) * (b - c). So for the solution you expect a with each value in the second parenthesis and b also. The solution looks like this: from - ac + b - bc.
- Have the following formula (a + b) ², is a simplified representation of the formula (a + b) * (a + b). They also called binomial formula. The solution is a² + 2ab + b.

### Factoring is the exact opposite

When factoring is exactly the opposite of calculation. A number can only be set before the clip if it occurs in any single number. Again, of course, the above-mentioned basic arithmetic apply. The easiest way to get to this calculation process, once you have mastered the multiplying.

- Take the above formula calculated from - ac and try to exclude these. The value a is present in each number and can therefore be excluded: a * (b - c).
- It is more difficult, of course, also in the prepared formula from - ac + b - bc. Since both a and b does not occur in any number, the formula is "divided" and it creates two brackets: (a + b) * (b - c).

Just try it. If you are not sure whether the factoring is actually correct, multiply the control simply back out - the latter should be able to expect safe in any case. After some practice you will see that what looks so complicated, is not so difficult.