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### Course: Algebra (all content)>Unit 3

Lesson 11: Interpreting linear functions and equations

# Linear graphs word problems

Sal discusses how we would go about making sense of the direction of a linear graph that represents a relationship between two real-world quantities. Created by Sal Khan.

## Want to join the conversation?

• if there was a third dimension would it be labeled z?
• Yes. It is labeled z. You can use it to plot three dimensional figures, such as cubes and pyramids, if you connect the dots. As for lines in the third dimension, you can have one independent variable and two dependent ones. With it.
• Why are some lines curved and some are straight?
• It really depends on the x and y values. So for example, a cup with a large bottom and thin top would have a curve on its graph of time and liquid
• What would a non linear graph look like?
• Non-linear graphs can refer to any other equations that can be graphed on a coordinate plane that are not in linear form: `y=mx+b`

Normally, this means that it will be a large polynomial equation.
With differently sized exponents per term, the graph can be manipulated into fantastic shapes and curves that are definitely not linear.

This is a good site to play around with that--
https://www.desmos.com/calculator
• Can a discrete graph also be continuous?
• hmm... I'm not QUITE sure if it can, probably not because
Continuous graphs represent functions that are continuous along their entire domain. These functions may be evaluated at any point along the number line where the function is defined. For example, the quadratic function is defined for all real numbers and may be evaluated in any positive or negative number or ratio thereof. Continuous graphs do not possess any singularities, removable or otherwise, in their domain, and possess limits across their entire representation.Discrete graphs represent values at specific points along the number line. The most common discrete graphs are those that represent sequences and series. These graphs do not possess a smooth continuous line but rather only plot points above consecutive integer values. Values that are not whole numbers are not represented on these graphs. The sequences and series that produce these graphs are used to analytically approximate continuous functions to any desired degree of accuracy.
• couldnt demand be negative
• I don't think it can.
Demand means that people want something so naturally the higher the demand for something, the higher the price gets. The lower the demand the lower the price.
But think about if demand were negative, it would mean that instead of a paying a price for getting something, you get paid instead.
• Can someone elaborate? I have the iq of a baked potato. :/
• Why are there letters?
• IF you are asking on graphs, they are there usually so you can identify them so later in the problem if they ask you
A. What is (5,5)
You can answer the letter S if S is at where (5,5) is.
Or
B. B (8,9)
You can put B on the place where (8,9) is.
• Is there a 3rd and 4th dimension in graphs? If so, then what would it be labeled?