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標題:
F4 maths y=-2x^2+3x-k-1
發問:
It is given that the graph of y=-2x^2+3x-k-1 cut the x axis at two points a)find the range of possible values of k b)hence, find the roots of the x intercepts of the graph for the largest integral value of k in (a)
(a) since y = -2x2 + 3x - k - 1 cuts the x axis at two points, the discriminant of -2x2 + 3x - k - 1 = 0 is greater than 0 Δ = (3)2 - 4(-2)(- k - 1) > 0 9 - 8k - 8 > 0 => 1 > 8k => k < 1/8 (b) for the largest integral of k in (a), k = 0, the parabola becomes y = -2x2 + 3x - 1. for x intercepts, y = 0 => -2x2 + 3x - 1 = 0 2x2 - 3x + 1 = 0 => (2x - 1)(x - 1) = 0 => x = 1/2 or x = 1
其他解答:
F4 maths y=-2x^2+3x-k-1
發問:
It is given that the graph of y=-2x^2+3x-k-1 cut the x axis at two points a)find the range of possible values of k b)hence, find the roots of the x intercepts of the graph for the largest integral value of k in (a)
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最佳解答:(a) since y = -2x2 + 3x - k - 1 cuts the x axis at two points, the discriminant of -2x2 + 3x - k - 1 = 0 is greater than 0 Δ = (3)2 - 4(-2)(- k - 1) > 0 9 - 8k - 8 > 0 => 1 > 8k => k < 1/8 (b) for the largest integral of k in (a), k = 0, the parabola becomes y = -2x2 + 3x - 1. for x intercepts, y = 0 => -2x2 + 3x - 1 = 0 2x2 - 3x + 1 = 0 => (2x - 1)(x - 1) = 0 => x = 1/2 or x = 1
其他解答:
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