To solve the problem, let's analyze the question:

We are tasked with writing an expression for the height of a tree, where:

• The tree starts at 9 feet.
• The height increases by 3 feet per year.
• $y$ represents the number of years.

Expression:

The height of the tree after $y$ years can be expressed as: $\text{Height} = 9 + 3y$

• The $9$ represents the initial height of the tree.
• The $3y$ accounts for the growth over $y$ years, where the tree grows 3 feet each year.

Answer:

The expression is: $9 + 3y$

Would you like further clarification or help with related concepts?

5 Related Questions:

1. How would the expression change if the initial height was 12 feet instead of 9 feet?
2. What if the tree grew by 5 feet per year instead of 3 feet?
3. How do you evaluate the height of the tree after 5 years using the expression $9 + 3y$?
4. Can you represent this relationship as a graph? What would it look like?
5. How can this concept be applied to real-world problems involving linear growth?

Tip:

When dealing with growth problems, always identify the starting value (constant) and the rate of change (coefficient of the variable).