Pre-Algebra: Chapter 5, Lesson 9
Arithmetic Patterns
Arihmetic patterns are patterns that have an addition or subtraction in the series or sequence of numbers. Patterns like 1, 4, 7, 10, 13 … are arithmetic because we add 3 to each number to get the next number. 1 + 3 = 4, 4 + 3 = 7 … Geometric patterns (these are not in the book yet) are patterns that have products or divisions to get the next series of numbers.
Algebra: Chapter 8, Lesson 5
D-R-T Problems (otherwise known as DIRT problems). D is the distance, R is the rate (or speed like miles per hour [mph] or kilometers per hour [kph] or feet per second [ft/sec]) and T is the time. Be careful and make sure that if the rate is in mph, then the time has to be in hours. If the rate is in feet/sec, then the time has to match and be in seconds as well.
For those type of problems that have 2 people starting off, remember that the first person’s time is “t”, but the second person (who leaves later) actually has t – x time where x is the time delay of the second person leaving. For example if one person leaves at “t” and the second leaves 2 hours later, then the second person’s time is “t – 2“.
Here are some links to excellent D-R-T examples at the PurpleMath website. Its easier to link to these than show you the same thing!