1)1/4/b^2=1,∴b=1/2;e^2=1-b^2/a^2=1-1/(4a^2)=3/4,解得a=1,所以椭圆方程x^2+4y^2=1.
2)将y=kx+1带入椭圆方程,x^2+4(kx+1)^2=1,(1+4k^2)x^2+8kx+3=0.Δ=64k^2-12-48k^2=16K^2-12=0,k=±√3/2
1)1/4/b^2=1,∴b=1/2;e^2=1-b^2/a^2=1-1/(4a^2)=3/4,解得a=1,所以椭圆方程x^2+4y^2=1.
2)将y=kx+1带入椭圆方程,x^2+4(kx+1)^2=1,(1+4k^2)x^2+8kx+3=0.Δ=64k^2-12-48k^2=16K^2-12=0,k=±√3/2