過(guò)拋物線y=ax^2(a>0)的焦點(diǎn)F作直線交拋物線于P、Q兩點(diǎn),若線段PF與QF的長(zhǎng)分別為p、q,則1/p+1/q=?
過(guò)拋物線y=ax^2(a>0)的焦點(diǎn)F作直線交拋物線于P、Q兩點(diǎn),若線段PF與QF的長(zhǎng)分別為p、q,則1/p+1/q=?
高手請(qǐng)進(jìn)!注意焦點(diǎn)是（0,1/4a)!
高手請(qǐng)進(jìn)!注意焦點(diǎn)是（0,1/4a)!
數(shù)學(xué)人氣：859 ℃時(shí)間：2019-10-17 05:50:52
優(yōu)質(zhì)解答
答：1/p+1/q=4a（可用特值y=1/4a 計(jì)算）.下面用一般方法：設(shè)斜率為k,直線方程為y=kx+1/4a,P(x1,y1),Q(x2,y2),由第二定義有y1=p-1/4a,y2=q-1/4a,又P、Q都在直線上,得到p=kx1+1/2a,q=kx2+1/2a.又P、Q是直線和曲線的交...
我來(lái)回答
類(lèi)似推薦
- 過(guò)拋物線y =ax^2(a>0)的焦點(diǎn)F作一直線交拋物線于P、Q兩點(diǎn),若線段PF與FQ的長(zhǎng)
- 過(guò)拋物線y²=2ax(a>0)的焦點(diǎn)F作一直線交拋物線于P,Q兩點(diǎn),若線段PF與QF的長(zhǎng)分別是m,n,則1／m+1／n=
- 過(guò)拋物線y=ax^2(a＞0)的焦點(diǎn)F作一直線交拋物線于P、Q兩點(diǎn),若PF與QF的長(zhǎng)分別是p、q,則1/p+1/q等于
- 過(guò)拋物線y=ax^2(a>0)的焦點(diǎn)F作直線交拋物線于P、Q兩點(diǎn),若線段PF與QF的長(zhǎng)分別為p、q,則1/p+1/q=?
- 過(guò)拋物線y=ax^2(a>0)的焦點(diǎn)F用以直線交拋物線于P,Q兩點(diǎn),若線段PF與FQ的長(zhǎng)分別是p、q,則1/p+1/q等于?
- 函數(shù)f(x)=sinx-cosx^2的最小值是?
- 英語(yǔ)翻譯
- I took my grandpa to the hospital this morning,_____ I missed the first class.
- So crazy
- 方差是各個(gè)數(shù)據(jù)與平均數(shù)之差的平方的平均數(shù)
- 函數(shù)y=f(x)與它反函數(shù)y=f^-1(x)怎么讀?
- These are photos of my families.Look at them 改錯(cuò)
猜你喜歡
- 1平面與平面重合,是否屬于平行一類(lèi)?那重合的兩直線,也屬于平行一類(lèi)的嗎?
- 2非洲每年因饑餓死亡的人數(shù)及現(xiàn)在饑餓人口數(shù)量拜托各位了 3Q
- 3decide to do sth.還=什么
- 4(7/8)o you think of london?B:5.____london is one of the liveliest cities
- 5啤酒可以托運(yùn)嗎
- 6邊長(zhǎng)為2√6的等邊三角形的中心到一邊的距離為?
- 7please give your hand to help me
- 8已知2的X次方等于3的Y次方等于6的Z次方不等等于1,證明X分之一加Y分之一等于Z分之一.
- 9幫我做做?
- 10機(jī)械分析天平TG628A的使用說(shuō)明書(shū)
- 11in winter ,we wear warm coats to protect our bodies_.
- 12( )was most importance to her ,she told me,was her family it this what as