When is something directly proportional

Use algebra to rewrite the equation. In this instance, the equation does not, so the variables are not directly proportional.

In fact, they are inversely proportional. Consider the following set of points. Are the variables directly proportional?

Compare the factor, or constant, of the two variables. They both grow by a factor of 3. Therefore, the variables are directly proportional. Does the graph show direct proportion between variables? Since the equation of the line is in slope-intercept form, it has a constant slope, meaning the line is straight. So potentially, the variables are directly proportional. So, the variables are not directly proportional.

A zero slope means there's no change at all; thus, no proportionality at all. Not Helpful 1 Helpful If you can express x and y by any of those equations, you know that x and y are inversely proportional to each other meaning that x goes up at the same rate that y goes down, or vice versa. Not Helpful 0 Helpful 6.

We call this a direct proportion. Not Helpful 1 Helpful 6. If by linear you mean a straight line on a graph, the answer is yes. Not Helpful 2 Helpful 5. It is a variable whose value "depends" on the value of another variable. You can't find the value of y until you know the value of x, so y is the dependent variable.

Not Helpful 3 Helpful 4. Not Helpful 3 Helpful 5. While on the other hand, two quantities are said to be in inverse proportion if an increase in one quantity leads to a decrease in the other, and vice-versa. The graph of direct proportion is a straight line while the inverse proportion graph is a curve. Look at the image given below to understand the difference between direct proportion and inverse proportion. To find the cost of 32 lb apples, we will use the direct proportion formula.

Solution: Let the amount received by Henry be treated as y and the number of hours he worked as x. Two quantities are said to be in direct proportion if an increase in one also leads to an increase in the other quantity, and vice-versa. Direct proportion, as the name suggests, indicates that an increase in one quantity will also increase the value of the other quantity and a decrease in one quantity will also decrease the value of the other quantity.

While inverse proportion shows an inverse relationship between the two given quantities. It means an increase in one will decrease the value of the other quantity and vice-versa. How long will it take 6 people to paint it? Assume everyone works at the same rate It is an Inverse Proportion: As the number of people goes up, the painting time goes down.

As the number of people goes down, the painting time goes up. Example: Proportional to x 2. Example: light and distance The further away we are from a light, the less bright it is. Accessed 12 Nov. More Definitions for directly proportional. See the full definition for directly proportional in the English Language Learners Dictionary. Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free! Log in Sign Up. Save Word. Definition of directly proportional.

Examples of directly proportional in a Sentence His earnings are directly proportional to the number of units he sells.