直线x-y+1=0被椭圆x²÷16+y²÷4=1截得的弦长为多少,

问题描述:

直线x-y+1=0被椭圆x²÷16+y²÷4=1截得的弦长为多少,

x-y+1=0y=x+1代入x²÷16+y²÷4=1x²÷16+(x+1)²÷4=1x²+4(x+1)²=165x²+8x-12=0根据韦达定理:x1+x2=-8/5,x1x2=-2/5(x2-x1)² = (x2+x1)² -4x1x2 = (8/5)²...