Step by step
The question
Question: find the constant of proportionality for the point (5, 2).
(5, 2)
Proportional means: y divided by x is always the same number.
We call that number k.
Then y = k times x.
proportional: y ÷ x is always the same
k = y ÷ x, y = kx
1 Divide y by x
x is 5 and y is 2.
So k is 2/5, which is 0.4.
= k = 25 = 0.4
2 Write the equation
y = k x, with k = 0.4.
So the equation is y = 0.4x.
= y = 0.4x
3 Check
Let's check: k times x should give each y.
0.4 times 5 is 2.
So the answer is right!
0.4 × 5 = 2
Let's look back.
First: divide y by x.
Then: write the equation.
Last: check.
Answer
= y = 0.4x