Given the hyperbola x ^ 2-4y ^ 2 = 4 and the point m (8,1), the straight line passing through the electric m intersects the hyperbola at two points a and B, and M is the midpoint of the line AB, the equation of the straight line is obtained

Given the hyperbola x ^ 2-4y ^ 2 = 4 and the point m (8,1), the straight line passing through the electric m intersects the hyperbola at two points a and B, and M is the midpoint of the line AB, the equation of the straight line is obtained


Let a (a, b), B (C, d)
a^2 - 4b^2 = 4 (1)
c^2 - 4d^2 = 4 (2)
M (8,1) is the midpoint of line AB, 8 = (a + C) / 2,1 = (B + D) / 2
a+c = 16,b+d = 2
(1)-(2):(a+c)(a-c) = 4(b+d)(b-d)
16(a-c) = 4*2(b-d)
(b-d)/(a-c) = 2
That is, the slope of AB is 2, and the equation is Y - 1 = 2 (x - 8)
y = 2x - 15



The line passing through point P (8,1) intersects hyperbola x2-4y2 = 4 at two points a and B, and P is the midpoint of line ab. the equation of line AB is obtained


Let a (x1, Y1), B (X2, Y2), then X1 + x2 = 16, Y1 + y2 = 2, ∵ x12-4y12 = 4, x22-4y22 = 4, ∵ 16 (x1-x2) - 8 (y1-y2) = 0, ∵ KAB = 2, ∵ the equation of straight line is Y-1 = 2 (X-8), that is, 2x-y-15 = 0



The line passing through point P (8,1) intersects hyperbola x2-4y2 = 4 at two points a and B, and P is the midpoint of line ab. the equation of line AB is obtained


Let a (x1, Y1), B (X2, Y2), then X1 + x2 = 16, Y1 + y2 = 2, ∵ x12-4y12 = 4, x22-4y22 = 4, ∵ 16 (x1-x2) - 8 (y1-y2) = 0, ∵ KAB = 2, ∵ the equation of straight line is Y-1 = 2 (X-8), that is, 2x-y-15 = 0



Through point a (6,1), make a straight line L and hyperbola 16 / x square - 4 / y square = 1, intersect at BC, and a and the midpoint of line BC, find l equation (point difference method)


Let B (x1, Y1), C (X2, Y2) and a (6,1) be the midpoint of BC, then: X1 + x2 = 12, Y1 + y2 = 2
Substituting B and C into hyperbola, we get the following result:
x1²/16-y1²/4=1
x2²/16-y2²/4=1
Results: (x1 & # 178; - x2 & # 178;) / 16 - (Y1 & # 178; - Y2 & # 178;) / 4 = 0
Then: (Y1 & # 178; - Y2 & # 178;) / (x1 & # 178; - x2 & # 178;) = 1 / 4
That is: (y1-y2) (Y1 + Y2) / (x1-x2) (x1 + x2) = 1 / 4
That is: 2 (y1-y2) / 12 (x1-x2) = 1 / 4
So: (y1-y2) / (x1-x2) = 3 / 2
That is: K (BC) = 3 / 2
Another point a (6,1)
So the equation of L is: 3x-2y-16 = 0
The test shows that there are two intersections between the straight line and hyperbola
So the equation of L is: 3x-2y-16 = 0