Twelve friends came to Guy's birthday party. He received seven gifts and a total of $95 in cash for his birthday. He buys an air
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Answer:
This is the shorthand way of writing
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Work Shown:
The plus or minus is needed because squaring a negative leads to a positive. As another example, x^2 = 25 has x = 5 and x = -5 as the two solutions. Note that x^2 = (-5)^2 = (-5)*(-5) = 25.
Also, note that the 80 was broken up into 16*5. This was done to simplify the square root. We pull out the largest factor that's a perfect square.
So that's how we get to the solution set . The curly braces tell the reader that they are dealing with a set.