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標題:
A MATHS (VERY URGENT)
發問:
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Solve this inequality by completing square and quadratic formula. Must show the steps clearly. 1. 2x - 3
最佳解答:
2x - 3 0 9(x^2 - 14x/9) + 7 > 0 9(x^2 - 14x/9 + 49/81) + 7 - 49/9 > 0 9(x - 7/9)^2 + 7 - 49/9 > 0 9(x - 7/9)^2 + 14/9 > 0 9(x - 7/9)^2 + 14/9 always positive x is any real number
其他解答:
completeing square: 2x - 3 0 9x^2 -14x >-7 9(x^2 - 14/9 x) > -7 9(x - 7/9)^2 - 49/9 > -7 9(x -7/9)^2 > -14/9 (x - 7/9)^2 >-14/81 no solution quadratic formula: 9x^2 -14x +7 > 0 x = [ 7 +- root (49 - 63*4) ] / 18 = no solution
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