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anemone
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Let $n$ be a positive integer. Show that if $2+2\sqrt{28n^2+1}$ is an integer, then it is a square.
A square number is a number that can be formed by multiplying two equal numbers together. For example, 4 is a square number because it can be formed by multiplying 2 x 2.
To prove that 2+2√(28n²+1) is a square number, we can use the definition of a square number. We need to show that it can be written in the form of (a+b)², where a and b are integers. By expanding (a+b)², we get a² + 2ab + b². In this case, a = 1 and b = √(28n²+1). Therefore, (a+b)² = 1 + 2√(28n²+1) + (28n²+1) = (1+√(28n²+1))². Since 1+√(28n²+1) is an integer, we have proven that 2+2√(28n²+1) is a square number.
Yes, 2+2√(28n²+1) is always a square number. This is because the expression can be simplified to (1+√(28n²+1))², and the square of any integer is always a square number.
No, 2+2√(28n²+1) is always a square number. Even if n = 0, the expression simplifies to 1, which is a square number.
Proving that 2+2√(28n²+1) is a square number is significant because it helps to understand the properties and relationships of different types of numbers. It also demonstrates the use of mathematical techniques and logic to solve problems and make conclusions.