Understanding Direct Proportionality

The video tutorial explains the concept of direct proportionality, where y is directly proportional to x, meaning y equals a constant times x. It demonstrates how to find the constant of proportionality (k) when given specific values of y and x. In this case, when y is 30 and x is 6, the constant k is calculated to be 5. The tutorial then uses this constant to solve for x when y is 45, resulting in x being equal to 9.

What does it mean when we say y is directly proportional to x?

• y is equal to a constant divided by x

• y is equal to x plus a constant

• y is equal to a constant times x

• y is equal to x squared

Tags

CCSS.7.RP.A.2B

If y is 30 when x is 6, what is the constant of proportionality?

• 6

• 3

• 4

• 5

Tags

CCSS.7.RP.A.2B

How do you find the constant of proportionality from given values of x and y?

• Divide y by x

• Subtract x from y

• Multiply y by x

• Add y and x

Tags

CCSS.8.F.B.4

CCSS.HSF.LE.A.2

What equation represents the relationship between y and x after finding the constant?

• y = 5 + x

• y = 5x

• y = x/5

• y = x - 5

Tags

CCSS.7.RP.A.2B

What is the value of x when y is 45, given the constant of proportionality is 5?

• 7

• 8

• 10

• 9

How do you solve for x when y is given in a direct proportionality equation?

• Divide y by the constant

• Multiply y by the constant

• Add the constant to y

• Subtract the constant from y