答:
设双曲线方程为
x^2/a^2-y^2/b^2=1
点(2,-3)代入得:4/a^2-9/b^2=1………………(1)
令x^2/a^2=y^2/b^2得:y/b=±x/a
y=±(b/a)x=±(2/3)x
b/a=2/3
所以:b=2a/3………………(2)
由(1)和(2)解得:
(16-81)/(4a^2)=1
a^2=-4/65
答:
设双曲线方程为
x^2/a^2-y^2/b^2=1
点(2,-3)代入得:4/a^2-9/b^2=1………………(1)
令x^2/a^2=y^2/b^2得:y/b=±x/a
y=±(b/a)x=±(2/3)x
b/a=2/3
所以:b=2a/3………………(2)
由(1)和(2)解得:
(16-81)/(4a^2)=1
a^2=-4/65