What is the equation of the directrix of the parabola x2 – 2x – 4y + 5 = 0?
回答 (3)
2015-11-08 12:22 pm
x^2-2x-4y+5= 0
(x^2-2x+1)-1 -4y+5 = 0
(x-1)^2 -4y-4=0
(x-1)^2 = 4y+4
(x-1)^2 = 4(y-1)
This is of the form
(x-h)^2 = 4p(y-k) ,where h=1, k=1
A parabola with vertex (1,1)
4p=4
p=1
Equation of the directrix is y=k-p
y = 1-1
y=0
(x^2-2x+1)-1 -4y+5 = 0
(x-1)^2 -4y-4=0
(x-1)^2 = 4y+4
(x-1)^2 = 4(y-1)
This is of the form
(x-h)^2 = 4p(y-k) ,where h=1, k=1
A parabola with vertex (1,1)
4p=4
p=1
Equation of the directrix is y=k-p
y = 1-1
y=0
2015-11-08 12:22 pm
Award this as best answer if you think adi is a knob
2015-11-08 12:04 pm
No
收錄日期: 2021-04-21 14:58:33
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https://hk.answers.yahoo.com/question/index?qid=20151108040251AA4AaOO