A square field has a side length of (x) metres. If the side is increased by 8 metres, the area increases by 1216 square metres. What is the value of (x)?
Answer and explanation
Correct answer: 72
The increase in area is ((x+8)^2-x^2=1216). Expanding gives (16x+64=1216), so (16x=1152) and (x=72) metres. Therefore, option B is correct. Exam tip: For a change in the side of a square, use ((x+a)^2-x^2=2ax+a^2); do not incorrectly set ((x+a)^2=1216).
Frequently asked questions
What is the correct answer to this question?
72
Why is this the correct answer?
The increase in area is ((x+8)^2-x^2=1216). Expanding gives (16x+64=1216), so (16x=1152) and (x=72) metres. Therefore, option B is correct. Exam tip: For a change in the side of a square, use ((x+a)^2-x^2=2ax+a^2); do not incorrectly set ((x+a)^2=1216).
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Quadratic Equations. Topic: Word Problems and Applications.
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