1)x^2/25-y^2/16=1=>a=5,b=4=>c=√41
焦點(diǎn)位置:x軸
實(shí)軸長2a=10
虛軸長2b=8
離心率e=c/a=√41/5
焦點(diǎn)(±√41,0)
頂點(diǎn)(±5,0)
漸進(jìn)線y=±(4/5)x
2)9x^2-y^2=81=>x^2/9-y^2/81=1=>a=3,b=9=>c=3√10
焦點(diǎn)位置:x軸
實(shí)軸長2a=6
虛軸長2b=18
離心率e=c/a=√10
焦點(diǎn)(±3√10,0)
頂點(diǎn)(±3,0)
漸進(jìn)線y=±3x
3)x^2-9y^2=1=>x^2-y^2/(1/9)=1=>a=1,b=1/3=>c=(√10)/3
焦點(diǎn)位置:x軸
實(shí)軸長2a=10
虛軸長2b=8
離心率e=c/a=√10/3
焦點(diǎn)(±(2√10)/3,0)
頂點(diǎn)(±2,0)
漸進(jìn)線y=±(1/3)x