设斜率是ky+1=k(x-2)y=kx-(1+2k)代入椭圆x²+4y²=16(4k²+1)x²-8k(1+2k)x+4(1+2k)²-16=0x1+x2=8k(1+2k)/(4k²+1)中点则x=(x1+x2)/2=4k(1+2k)/(4k²+1)横坐标是2所以4k(1+2k)/(4k&sup...