The line y=x-5 cuts the graph of 3y^2 + 2x - k = 0 at the points (x1,y1) and (x2,y2)
respectively. It is known that 3 x1x2 = 64
a) find the value of k
b) Hence, solve 3y^2 + 2x - k = 0
y = x-5
F.4 1 Maths Question
2013-03-27 3:52 am
回答 (1)
2013-03-27 5:24 am
✔ 最佳答案
3y^2 + 2x - k = 03(x - 5)^2 + 2x - k = 0
3x^2 - 28x + 75 - k = 0
So, x1x2 = (75 - k)/3
As 3x1x2 = 64 => 75 - k = 64 => k = 11
(b) The equation becomes
3x^2 - 28x + 64 = 0
(3x - 16)(x - 4) = 0
x = 16/3 or x = 4
So, two intersection points are (4,-1), (16/3,1/3)
收錄日期: 2021-04-27 17:44:46
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