1. What are the proportion and graphs?
Proportions and graphs are ways to represent the relationship between two quantities. Once you know the kind of proportional relationship between two variables with each other, you can judge what kind of graphs you will get just by looking at the relation or vice-versa.
1.1 Important direct proportionality graphs
When two variables are in direct proportion with each other, an increment in one variable leads to an increment in another in the same proportion, the same must be visible in their graphs as well.
1.2 Important inverse proportionality graphs
When two variables are inversely proportional to each other, an increment in one variable leads to a decrement in another in the same proportion, the same must be visible in their graphs as well.
Examples:
These graphs show different relationships between the variables x and y.
Identify the graph which shows the following.
- y is directly proportional to x2
Only Figure A shows that y ∝ x2.
- y is directly proportional to √x
Only Figure C shows that y ∝ √x.
