Topic Details (Notes format)

How to Solve Direct and Inverse Variation Problems

Subject: Mathematics

Book: Maths Mastery

Direct variation follows y = kx, where y changes proportionally with x (e.g., doubling x doubles y). Inverse variation follows y = k/x, implying that multiplying x by a factor divides y by the same factor. For instance, if y ∝ x, you might have y = 3x; doubling x from 2 to 4 changes y from 6 to 12. Conversely, if y ∝ 1/x, and x changes from 2 to 4, y becomes half. Variation problems are integral in physics (Ohm’s Law), chemistry (pressure-volume relationships), and everyday concepts like speed-time relationships. Mastering them helps you interpret how one quantity shifts in response to another.

Practice Questions

If a = 5 and b = 12, what is the length of the hypotenuse of a right triangle?

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The sides of a triangle are 5 cm, 12 cm, and 13 cm. What type of triangle is it?

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A rectangle has a length of 10 cm and a width of 5 cm. What is the diagonal of the rectangle?

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What is the sum of all even numbers between 1 and 100?

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What is the 7th term of the arithmetic progression 3, 6, 9, 12,...?

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What is the HCF of 72 and 120?

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If the radius of a circle is 7 cm, what is its circumference?

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If x:y = 2:3 and z:y = 4:3, what is x:z?

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If the sides of a triangle are 6 cm, 8 cm, and 10 cm, what is the area of the triangle?

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How many diagonals does a pentagon have?

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