2. Essential Understanding: some quantities are
in a relationship where the ratio of
corresponding values is constant
Objectives:
Students will be able to write and interpret direct
variation equations
3. Algebra
A-CED.2. Create equations in two or more variables to represent
relationships between quantities; graph equations on coordinate
axes with labels and scales.
Functions
F-IF.1. Understand that a function from one set (called the domain)
to another set (called the range) assigns to each element of the
domain exactly one element of the range. If f is a function and x is
an element of its domain, then f(x) denotes the output of f
corresponding to the input x. The graph of f is the graph of the
equation y = f(x).
F-BF.1. Write a function that describes a relationship between two
quantities.★ Determine an explicit expression, a recursive process,
or steps for calculation from a context.
4. You are building a roof. You mark off four
equal intervals from along the base and place
vertical posts as shown below. What are the
heights of the four vertical posts? Explain.
How are the base and height of the largest
triangle related?
How can you find the height
of the smallest triangle?
What is the relationship
between each post?
5. In an equation, as the input increases or
decreases, the output increases or decreases
proportionally
y = kx, where k ≠ 0 and x represents input
values and y represents the output values
K is called the constant of variation
How could you find k if you know x and y?
6. Determine if there is a direct relationship, if
so what is the constant of variation?
7. For each function determine if y varies
directly with x. If so, what is the constant of
variation?
5x + 3y = 0
y = x/9
8. Suppose y varies directly with x, and y = 15
when x = 3. What is why when x = 12?
What do you need to find first?
The number of Calories varies directly with
the mass of cheese. If 50 grams of cheese
contains 200 Calories, how many Calories are
in 70 grams of cheese?
