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## Get ready for Algebra 1

### Course: Get ready for Algebra 1>Unit 4

Lesson 2: Patterns with variables

# Graphing sequence relationships

Sal plots ordered pairs based on sequence relationships.  Created by Sal Khan.

## Want to join the conversation?

• Is there a way to describe both sequences simultaneously in a single expression?
• Not really, because you need an equation to describe how x gives you y. To do this you need an equation. 5x by itself would be considered an expression. But that is not enough info to give you the sequence for getting y. You need the "equation" 5x=y to describe the sequences for x and y to plot them. Hope this helps. :)
• Can anybody tell me why x and y are traditional letters?
• because coordinate planes is normally used to represent data but when someone is using it with no data the axes are unknown so people use letters to represent the unknown so the axis x is unknown or not assigned and axis y is unknown or not assigned. so people use letters as a placeholder. I wish I helped
• Can someone help me? I can't figure out the following challenge Visualizing and interpreting relationships between patterns. If you see this please answer! Thanks for your time
• Think of the plot area as two number lines. The first number in an ordered pair goes to the right and the second number in an ordered pair goes number goes up. (Right UP!). Easy enough to plot on the graph. That's the easy part. The part you might be having problems with is finding out the relationship between the numbers.

Example

Sequence X: Start at the number 5 and the rule is add one. So sequence X would read 5, 6, 7, 8, 9 and so on.
Sequence Y: Start at the number 10 and the rule is add two. So the sequence Y would read 10, 12, 14, 16, 18 and so on.
Your ordered pairs would be (5,10) (6,12) (7,14) (8,16) (9,18)
Do you notice a pattern? 5x2=? 6x2=?
Could you say that the numbers on the Y axis are two times as large? I hope this helps some.
• math is very fun in my opinion!!
• learning it is not
(1 vote)
• you are boring got it add more fun to it
• This program is named after him,Sal Khan!
This is cray-z!
• why does X go first? and how does this apply in real life?
• Hi, the way I usually explain this to my students by comparing it to the rules of the road. Why does everybody drive on the left in the UK (or the right in the US)? Because if everybody drove where they wanted it would be chaos. So I tell my students that mathematicians decided to always write X first. This way, if you had to whatsapp coordinates to someone in Fiji he or she will know what you meant and if they sent you coordinates you would be able to plot them the way the your Fijian friend meant. So it's basically convention so that we can communicate clearly, no matter where we're from.

How does this apply to real life? Oh, some of the most beautiful maths in the world is based on this. This is one of the first skills that you learn that eventually becomes calculus and calculus is the maths that people used to put a man on the moon and describe the motion of stars*. You are literally on the path to learning rocket science. Isn't that amazing? *(I'm over-simplifying but I think you get the idea).