設y=3x-7 y=2x平方-4x-2 兩圖形交點為A B求AB長 答案2/3根號10 求算式?
回答 (2)
2016-10-16 2:58 am
y=3x-7
y=2x^2-4x-2
(x,y)=(5/2,1/2)
(x,y)=(1,-4)
AB=[(5/2-1)^2+(1/2+4)^2]^0.5
AB=(9/4+81/4)^0.5
AB=(100/4)^0.5
AB=5
y=2x^2-4x-2
(x,y)=(5/2,1/2)
(x,y)=(1,-4)
AB=[(5/2-1)^2+(1/2+4)^2]^0.5
AB=(9/4+81/4)^0.5
AB=(100/4)^0.5
AB=5
2016-10-09 11:22 am
Sol
y=3x－7=2x^2－4x－2
3x－7=2x^2－4x－2
2x^2－7x+5=0
(2x－5)(x－1)=0
x=5/2 or x=1
(1) x=5/2
y=3*5/2-7=1/2
(2) x=1
y=3*1－7=－4
AB^2=(5/2－1)^2+(1/2+4)^2
=(3/2)^2+(9/2)^2
=9/4+81/4
=90/4
AB=√90/2=3√10/2
y=3x－7=2x^2－4x－2
3x－7=2x^2－4x－2
2x^2－7x+5=0
(2x－5)(x－1)=0
x=5/2 or x=1
(1) x=5/2
y=3*5/2-7=1/2
(2) x=1
y=3*1－7=－4
AB^2=(5/2－1)^2+(1/2+4)^2
=(3/2)^2+(9/2)^2
=9/4+81/4
=90/4
AB=√90/2=3√10/2
收錄日期: 2021-04-18 15:41:32
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20161009001114AAmxVFK