|
Suppose
you were given an equation like
2x – 3 = 5.
You
will need to use the addition principle
to move the –3, and the multiplication
principle to remove the coefficient 2.
Which one should you use first? Strictly
speaking, it does not matter—you will
eventually get the right answer. In practice,
however, it is usually simpler to use
the addition principle first, and then
the multiplication principle. The reason
for this is that if we divide by 2 first
we will turn everything into fractions:
Given:
2x – 3 = 5
Suppose
we first divide both sides by 2:
Now
there is nothing wrong with doing arithmetic
with fractions, but it is not as simple
as working with whole numbers. In this
example we would have to add 3/2 to both
sides of the equation to isolate the x.
It is usually more convenient, though,
to use the addition principle first:
Given:
2x – 3 = 5
Add
3 to both sides:
At this point all we need to do is divide both
sides by 2 to get x = 4.
|
