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關於S.1 Maths =]
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1)Consider the expression (-1)x(-1)x(-1)x......x(-1).What is the value if the number of -1`s is odd? What if the number of -1`s is even?Explain your answer briefly.2)Use a ruler and a protract to draw 3 lines AB,BC and CD such that BC⊥AB and BC⊥CD.Are AB and CD parallel to each other?Explain your... 顯示更多 1)Consider the expression (-1)x(-1)x(-1)x......x(-1).What is the value if the number of -1`s is odd? What if the number of -1`s is even?Explain your answer briefly. 2)Use a ruler and a protract to draw 3 lines AB,BC and CD such that BC⊥AB and BC⊥CD.Are AB and CD parallel to each other?Explain your answer briefly. 3)Given that the distance between A(-5,-2) and B(x,-2) is 6 units.Are the coordinates of B unique?Explain your answer briefly. PLZ詳細地解答. 15點=]
最佳解答:
1) If the number of -1's is X, where X is odd number. When X = 5, (-1)(-1)(-1)(-1)(-1) = 1 * 1 * (-1) = -1 If the number of -1's is Y, where Y is even number. When Y = 4, (-1)(-1)(-1)(-1) = 1 * 1 = 1 So, if the number of -1's is odd number, then the answer is -1 if the number of -1's is even number, then the answer is 1. 2) So, just like a rectangle, A B D C So, see? AB⊥CD 3) The x-coordinate of B = - 5 + 6 = 1 And, -5 - 6 = - 11 So, the coordinates of B (1 , -2) (-11 , -2) So, the coordinates of B isn't unique.
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