Math Problem Statement

y varies directly as x and inversely as the square of z. y = 8 when x = 36 and z = 6. Find y when x = 2 and z = 8.

Solution

We are given the following information:

  • yy varies directly as xx and inversely as the square of zz, so the relationship can be written as:

y=kxz2y = k \cdot \frac{x}{z^2}

where kk is a constant of proportionality.

  • We know that y=8y = 8 when x=36x = 36 and z=6z = 6. First, we will substitute these values into the equation to find kk.

Step 1: Find the constant kk

8=k36628 = k \cdot \frac{36}{6^2} 8=k3636=k8 = k \cdot \frac{36}{36} = k So, k=8k = 8.

Step 2: Find yy when x=2x = 2 and z=8z = 8

Now that we know k=8k = 8, we can substitute x=2x = 2 and z=8z = 8 into the equation to find yy.

y=8282y = 8 \cdot \frac{2}{8^2} y=8264y = 8 \cdot \frac{2}{64} y=8132=832=14y = 8 \cdot \frac{1}{32} = \frac{8}{32} = \frac{1}{4}

Thus, y=14y = \frac{1}{4}.

Would you like more details on any step?


Here are some related questions to extend your learning:

  1. What happens to yy if both xx and zz are doubled?
  2. How would the equation change if yy varies inversely as the cube of zz instead of the square?
  3. If yy varies directly as xx and inversely as zz, how would the solution method differ?
  4. How does the value of yy change if xx is halved and zz remains constant?
  5. Can we generalize the formula for other types of variations, such as quadratic or cubic dependence?

Tip: Always express variations clearly before solving the problem, as it guides the setup of the equation properly.

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Math Problem Analysis

Mathematical Concepts

Direct Variation
Inverse Variation
Algebra

Formulas

y = k * (x / z^2)

Theorems

Proportionality Theorem

Suitable Grade Level

Grades 9-10