# Evaluate the following expression: #4-7-:(3+1)-3-2*(5-9)+1# By how much does the value of the expression change if the parentheses are removed?

##### 1 Answer

#### Answer:

This is the change in the value of the expression.

#### Explanation:

The best way to approach calculations involving mixed operations, is to realise that there are "powerful" operations and "weak" operations.

The strongest operations are **powers and roots** ,

then come **multiplication and division** ;

the weakest are **addition and subtraction.**

They are therefore done in this order.

However, sometimes a weaker operation must be done first and that is indicated with parentheses, or brackets.

**ALWAYS count the number of terms first!!** (They are separated by the + and - signs).

There must be a final answer for each term, only then can they be added or subtracted - usually working from left to right, although this can be changed, using the commutative law, to make computation easier.

This is what is indicated by BODMAS, PEDMAS, etc.

In

=

Without the parentheses, there are 7 terms:

=

=

=

=

The difference between the two answers is

=

=