Writing a Proportional Equation from Known Values
Writing a Proportional Equation from Known Values is a Grade 7 math skill in Illustrative Mathematics, Chapter 2: Introducing Proportional Relationships. Students use a known (x, y) pair from a proportional relationship to calculate the constant of proportionality k and write the equation y=kx.
Key Concepts
If you know one pair of corresponding values $(x, y)$ from a proportional relationship (where $x \neq 0$), you can find the constant of proportionality $k$ by calculating $k = \frac{y}{x}$. The equation for the relationship is then $y = kx$.
Common Questions
How do you write a proportional equation from known values?
Divide the y-value by the x-value to find the constant of proportionality k. Then write the equation y equals k times x.
What is the constant of proportionality?
The constant of proportionality k is the ratio y/x in a proportional relationship. It tells you how much y changes for each unit increase in x.
What is an example of writing a proportional equation?
If 4 pounds of apples cost $6, then k equals 6 divided by 4 equals 1.5. The equation is y equals 1.5x, where x is pounds and y is cost in dollars.
How do you verify your proportional equation is correct?
Substitute a known value pair back into the equation. If the equation holds true, your constant of proportionality is correct.
What chapter covers writing proportional equations in Illustrative Mathematics Grade 7?
Writing proportional equations from known values is covered in Chapter 2: Introducing Proportional Relationships in Illustrative Mathematics Grade 7.