Could someone help correct my math problems?

Question

A. 2(4)-8/2+8

 

and i got 0/10 which is 0

 

B. 3(-5-3)+4(7-9)/5(-2)+3(-4)

 

and got 16/11

 

C. 2/5(5x+10)

 

and got 2x+4

 

D. A(1-1/A)

and got A/1-1

 

 

Answer 1

For B:

 

3(-5-3)+4(7-9)/5(-2)+3(-4)

 

Simplify within parenthesis: 3(-8) + 4(-2)/5(-2) + 3(-4)

 

Do multiplication or division from left to right: -24 + (-8)/5(-2) - 12

                                                                       -24 + (-1.6)(-2) - 12

                                                                       -24 + 3.2 - 12

 

Finally do addition from left to right: -32.8

 

As a check, if possible see what happens when this is put into a calculator

Answer 2

One must follow the Order of Operations:

The acronym to remember is PEMDAS

This stands for Parenthesis, Exponents, Multiplication & Division, Addition & Subtraction

 

You can remember PEMDAS by "Please Excuse My Dear Aunt Sally"

First work through parenthesis .. following the order of operations within the parenthesis.

Next work any exponents

Next work multiplication and division left to right as encountered

Finally work all addition and subtraction left to right

 

A. 2(4)-8/2+8   No exponents, one parenthesis which is a multiplication

                        Do the multiplication and division giving:

    8 - 4 + 8       Perform the addition and subtraction

    4+8

    12

 

B. 3(-5-3)+4(7-9)/5(-2)+3(-4)   work parenthesis first
    3(-8)+4(-2)/(-10) -12             perform mult/division left to right

    -24 + -8/(-10) -12

     -24 + 4/5 -12

      -36 + 4/5

       -35 1/5 or -176/5

 

C. 2/5(5x+10)

    2/[5(5x)+5(10)]

    2/(25x+50)

 

Or... Is this supposed to be:

 (2/5)(5x+10) ??

 = 2(5x+10)/5

 = [2(5x)+2(10)]/5

 = (10x + 20)/5

 = 10x/5 + 20/5

 = 2x + 4 

 

D. A(1-1/A)

    = A(1) + A(-1/A)

    = A - A/A

    = A - 1

 

Let me know if you need further assistance.  Good luck.

Answer 3

In order to check yourself, you need to follow the order of operations, PEMDAS.

 

Parenthesis

Exponents

Multiply or Divide from left to right

Add or Subtract from left to right

 

 

I will check the first one for you so that you understand the process.  Then you check the rest yourself and compare your original answers after the check.

 

A)

 

2(4) - 8/2 + 8

 

 

The first thing we can do here is multiply.  That is 2(4).

 

8 - 8/2 + 8

 

 

Then we can divide.  That is 8/2

 

8 - 4 + 8

 

 

Then we subtract because subtraction comes before addition in this expression.

 

4 + 8

 

 

Now all that is left is addition.

 

12

 

 

Now correct the rest of the problems on your own and see what you get.