| |
When an expression contains more than one operation, you can get different answers depending
on the order in which you solve the expression. We often use grouping symbols, like parentheses,
to help us organize complicated expressions into simpler ones. Here's the order we use:
1. First, do all operations that lie inside parentheses.
2. Next, do any work with exponents or roots.
3. Working from left to right, do all multiplication and division.
4. Finally, working from left to right, do all addition and subtraction.
Example:
Greatest Common Factors (GCF):
(GCF) of each number.
Example: Factors of 30 are 2, 3, and 5
And Factors of 130 are 2, 5, and 13
So, the common factors of 30 and 130 are 2 and 5. The GCF is 2×5 = 10.
Least Common Multiple (LCM):
(LCM) of each number.
Example: Factors of 8 are 2, 2, and 2
And Factors of 12 are 2, 2, and 3
For finding the common factors, we multiply all the factors, using the common factors only once.
So, the LCM of 8 and 12 is 2 × 2 × 2 × 3 = 24
We use ratios to make comparisons between two things. When we express ratios in words, we
use the word "to" -- we say "the ratio of something to something else." Ratios can be written in
several different ways: as a fraction, using the word "to", or with a colon.
For example: Ratio of circles to triangles is 6:3 or 2:1
Example: Jeannine has a bag with 3 videocassettes, 4 marbles, 7 books, and 1 orange.
What is the ratio of videocassettes to the total number of items in the bag?
Solution: There are 3 videocassettes, and 3 + 4 + 7 + 1 = 15 items total. The answer can be
expressed as 3/15, 3 to 15, or 3:15.
|
|
