Mathematics
Grade 11
15 min
Solve variation equations: Set 1
Solve variation equations: Set 1
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1
Introduction & Learning Objectives
Learning Objectives
Translate verbal statements of direct variation into an algebraic equation.
Translate verbal statements of inverse variation into an algebraic equation.
Calculate the constant of variation, k, given a set of conditions.
Write the specific equation that models a given variation relationship.
Use a variation equation to find an unknown value when other values are provided.
Distinguish between direct and inverse variation from a problem description.
Model a real-world scenario using a direct or inverse variation equation.
Ever notice that the more you study for a test, the higher your score tends to be? 📈 That relationship is a perfect example of variation!
Variation describes how one quantity changes in relation to another. In this tutorial, we will foc...
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Key Concepts & Vocabulary
TermDefinitionExample
VariationA mathematical relationship between two or more variables where a change in one variable results in a predictable change in the other(s).The relationship between distance, speed, and time is a form of variation.
Direct VariationA relationship between two variables, x and y, where their ratio is a constant. As one variable increases, the other increases proportionally.The cost of buying apples (C) varies directly with the weight of the apples purchased (w). If apples are $2 per pound, the equation is C = 2w.
Inverse VariationA relationship between two variables, x and y, where their product is a constant. As one variable increases, the other decreases proportionally.The time (t) it takes to travel a fixed distance varies inversely with your speed (s). The fas...
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Core Formulas
Direct Variation Formula
y = kx
Use this formula when a problem states that 'y varies directly as x' or 'y is directly proportional to x'. Here, k is the constant of variation, and k ≠0.
Inverse Variation Formula
y = \frac{k}{x} \quad \text{or} \quad xy = k
Use this formula when a problem states that 'y varies inversely as x' or 'y is inversely proportional to x'. Here, k is the constant of variation, and k ≠0.
4 more steps in this tutorial
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Challenging
The intensity I of a sound varies inversely as the square of the distance d from the source. If the intensity is 100 units at a distance of 3 meters, what is the intensity at a distance of 10 meters?
A.30 units
B.3 units
C.9 units
D.11.1 units
Challenging
The frequency f of a vibrating string varies inversely as its length L. A 60 cm string has a frequency of 256 Hz. What length of string would be required to produce a frequency of 320 Hz?
A.75 cm
B.48 cm
C.50 cm
D.40 cm
Challenging
The cost C of a pizza varies directly with the square of its radius r. A pizza with a 7-inch radius costs $12.25. What is the cost of a pizza with a 10-inch radius?
A.$17.50
B.$28.57
C.$25.00
D.$14.75
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