Kaj so tocke, fokus in directrix 9y = x ^ 2-2x + 9?

Odgovor:

Vertex #(1, 8/9)#

Osredotočite se #(1,113/36)#

Directrix # y = -49 / 36 #

Glede na -

# 9y = x ^ 2-2x + 9 #

vertex?

Osredotočite se?

Directrix?

# x ^ 2-2x + 9 = 9y #

Da bi našli Vertex, Focus in directrix, moramo ponovno napisati dano enačbo v vertexni obliki, tj. # (x-h) ^ 2 = 4a (y-k) #

# x ^ 2-2x = 9y-9 #

# x ^ 2-2x + 1 = 9y-9 + 1 #

# (x-1) ^ 2 = 9y-8 #

# (x-1) ^ 2 = 9 (y-8/9) #

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Poiskati enačbo v smislu # y # To ni vprašanje v težavi

# 9 (y-8/9) = (x-1) ^ 2 #

# y-8/9 = 1 / 9. (x-1) ^ 2 #

# y = 1/9. (x-1) ^ 2 + 8/9 #

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Uporabimo # 9 (y-8/9) = (x-1) ^ 2 # da bi našli točko, fokus in directrix.

# (x-1) ^ 2 = 4 xx 9/4 (y-8/9) #

Vertex #(1, 8/9)#

Osredotočite se #(1,(8/9+9/4))#

Osredotočite se #(1,113/36)#

Directrix # y = 8 / 9-9 / 4 #

Directrix # y = -49 / 36 #