SUBTRACTION is ADDING THE OPPOSITE

At least once in an Algebra Class the students should
see the "WHY" 
in SUBTRACTION becoming ADDING THE OPPOSITE
 in 7 - (-3) becoming 7 + (+3)
*****************************

Adding Positive and Negatives

Before starting a new topic try
the review question at the LEFT.

The answers are at the end of this blog!

****************

****ADDING POSITIVE AND NEGATIVES*****

**************ADDITION OF NUMBERS***********
When we ADD two POSITIVES it is just
our basic ADDITION and the ANSWER IS POSITIVE.
When we ADD two NEGATIVES
(Loss plus another Loss is a LOSS)
just ADD the two numbers and the ANSWER IS NEGATIVE.
so the obvious is just plain OBVIOUS:

(-) plus (-) is = (-)
(+) plus (+) is = (+)

A decision about "LARGER in SIZE"
is necessary when ADDING OPPOSITE SIGNS
(we actually subtract the SIZE):

(+) plus (-) is = (+) as long as the (+BIGGER)

(-) plus (+) is = (+) as long as the (+BIGGER)

(-) plus (+) is = (-) as long as the (-BIGGER)

(+) plus (-) is = (-) as long as the (-BIGGER)

***********try the sample problems below******

*************ANSWERS**************

*****ANSWERS TO PMDAS REVIEW*****

Which operation should we do first?

When we are faced with an EXPRESSION to be simplified, sometimes there are many operations (+, - , *, /)
within the expression.
For example how do we handle:   "2 PLUS 3 TIMES 4"
Without commas we do not know which operation to perform first.
---Do we Add 2 and 3 and then multiply by 4?
---OR should we multiplying 3 times 4 and then adding 2?
Mathematicians have come to an agreement that we will
MULTIPLY first and then ADD in this kind of problem.

First Grade Algebra

*****I*LOVE*MATH*****
Ever since you learned
how to ADD in the
first grade you have
been doing Algebra.

Remember those pages
where you had to write
a number into an
empty square with a
to make
the equation "TRUE"?

That was ALGEBRA!


**********************************

**************************

When you are finished trying these problems,
I will put the correct answers here:
5) x = 4
6) y = 3
7) z = 8
8) w = 5
9) A = 4
10) B = 7

If #10) was written as
3 times B = 21
the solution would be the same.
We will find out later that
B+B+B is 3 times B or 3B