B Why is \( (1 + \sqrt{-5}) \times (1 - \sqrt{-5}) \) Equal to 6?

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The expression \( (1 + \sqrt{-5}) \times (1 - \sqrt{-5}) \) simplifies to 6 through the difference of squares formula. By expanding the expression, it can be calculated as \( 1 - (-5) \), resulting in 6. Understanding imaginary numbers is not necessary to perform the calculation, but it can aid comprehension. The original question contained a typo regarding brackets, which was later corrected. The discussion concluded after clarifying the solution, as further engagement was deemed unnecessary.
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Why is (1 + sqrt(-5) x (1 – sqrt(-5)) equal to 6?
 
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Did you expand the expression?

Do you know about imaginary numbers? You don't have to to calculate the expression, but it helps understanding what is going on.
 
I don't know how to work with imaginary numbers.
 
Then just imagine that sqrt(-5) is some number that you don't know. You don't have to use imaginary numbers to solve the problem.
 
Typo in my original question - a right bracket is missing. It should be,
Why is (1 + sqrt(-5)) x (1 – sqrt(-5)) equal to 6?

Anyone?
 
mfb said:
Did you expand the expression?
 
You just have a difference of squares: (a+b)(a-b) = a^2-b^2 which, in your case means: (1 + sqrt(-5)) (1 – sqrt(-5)) = 1 - (-5)
 
Since Juan has shown the OP how to do this, and the OP keeps refusing to show any effort, this thread is now closed (after some cleanup)
 

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