Question

i need help with evaluating expressions and i have no idea how to can some one please help

Answer 1

Please clarify what kind of expressions... algebraic, numeric, trigonometric...
For numeric expressions, use PEDMAS (or PEMDAS), see, for example:
http://www.purplemath.com/modules/orderops.htm

Answer 2

algebraic i think

Answer 3

\[(2 \times 3)^2 \times -8 - 4(4+10)^2 + 8\]

Answer 4

This is numeric, you would use PEMDAS.
The order of evaluation is very important, PEMDAS stands for
P=parentheses, anything inside brackets are evaluated first
E=exponentiation, like squares, cubes, etc. are evaluated next.
MD = multiplications and divisions, next in order. If multiplications & divisions follows one another, do from left to right.
AS = addition and subtraction, last in order. If they follow one another, do from left to right.
Again,
http://www.purplemath.com/modules/orderops.htm
explains clearly with examples.

Example:
\((3 + 4)^2 \times (2) - 4(1+2)^2 + 3\)
evaluate expressions inside brackets:
\((7)^2\times 2 -4(3)^2+3\)
next, do exponentiation
\(49\times 2-4\times 9+3\)
next do multiplications (and divisions, if any)
98-36+3
next do additions and subtractions, from left to right
62+3
=65 is the final answer.