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In a rectangle model, the length is (x+6) and the breadth is (x-2). What is the total area after adding the parts?

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Answer and explanation

Correct answer: (x^2+4x-12)

The rectangle’s area is the product of its length and breadth: \\( (x+6)(x-2)\\). Multiplying each part gives \\(x\cdot x=x^2\\), \\(x\cdot(-2)=-2x\\), \\(6\cdot x=6x\\), and \\(6\cdot(-2)=-12\\). Combining like terms gives \\(x^2-2x+6x-12=x^2+4x-12\\). In a signed visual model, the negative width creates negative regions, so their signs must be retained when areas are combined algebraically.

Therefore option A is correct. The middle terms combine to \\(4x\\), and the constant corner is negative \\(-12\\). Option B incorrectly adds the two x-products as if both were positive. Option C reverses the signs of the middle and constant terms, while option D treats the constant product as positive. Careful distribution and sign handling lead directly to the stated total area.

Related tags

Rectangle ModelSigned AreasProduct Identity

Frequently asked questions

What is the correct answer to this question?

(x^2+4x-12)

Why is this the correct answer?

The rectangle’s area is the product of its length and breadth: \\( (x+6)(x-2)\\). Multiplying each part gives \\(x\cdot x=x^2\\), \\(x\cdot(-2)=-2x\\), \\(6\cdot x=6x\\), and \\(6\cdot(-2)=-12\\). Combining like terms gives \\(x^2-2x+6x-12=x^2+4x-12\\). In a signed visual model, the negative width creates negative regions, so their signs must be retained when areas are combined algebraically.

Therefore option A is correct. The middle terms combine to \\(4x\\), and the constant corner is negative \\(-12\\). Option B incorrectly adds the two x-products as if both were positive. Option C reverses the signs of the middle and constant terms, while option D treats the constant product as positive. Careful distribution and sign handling lead directly to the stated total area.

Which subject and chapter does this question cover?

This is a Class 9 Mathematics question. Chapter: Exploring Algebraic Identities. Topic: Visual models of identities.

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