I took a non-negative integer, and I add 1 to it, I then multiply this new number by 4. Finally, I add this latest number by the square of my original number.
Which of the following could not be my new latest number?
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Nice solution! However, just because the solution is a perfect square, you can't say that all perfect squares are solutions. For example, 0 and 1 cannot be achieved even though they are perfect squares. But that is an easy logical step to make. Good job!
The whole expression is equivalent to: 4 ( x + 1 ) + x 2 = 4 x + 4 + x 2 Then we have to check out the option which doesn't give an integral solution for x . Let us try 4 0 1 : x 2 + 4 x + 4 = 4 0 1 ⇒ x = 4 0 1 − 2 or x = − 2 − 4 0 1 And we are done!!
I see that your method is trial and error. So you should try the other choices too. You have only checked 401.
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i had checked all, but to save time writing the solution, i just took 401
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@Ashok Dargar Ok. :)
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@Munem Shahriar – But, clearly, yours is better...
Upvoted!!
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Suppose my original non-negative integer is x . The expression becomes
4 ( x + 1 ) + x 2
Which is a perfect square.
From the given options, 4,441,400 are perfect squares. But 401 is not a perfect square.
Hence 401 could not be my new latest number.