1, arithmetic progression, the first term of 8,4,0, ... = 8, tolerance d= -4.
2. The distance from (1,-3) to the straight line y=2x+5 is 25.
3. In geometric series, the common ratio is the ratio of the second term of geometric series to the adjacent previous term.
4. Sequence 20, 18, 16, 14. . . The general formula is: an=22-2n.
5. If, then =
6. If the straight lines y=3x+ 1 and x+By+C=0 are parallel to each other, then B=-1/3.
7. If the straight line is perpendicular to the straight line, the product of the slopes of the two straight lines =-1.
8. the oblique equation of a straight line is: y = kx+B.
9. It is known that the straight line passes through point A (1, 2) and the inclination is, then the equation of the straight line is: y-2=tan inclination (x- 1).
10, the general formula of known sequence is an = n (n+ 1), and a7+a 10= 166.
1 1, arithmetic progression, then _ _ _ _ _ _ _
12, if the series is known, then = _ _ _ _ _ _ _ _ _ _
13, the equation of the parabola with the focus of (3,0) is: y= 12x.
A general formula of 14 and arithmetic progression-1, 2, 5, … is: an= 3n-4.
15. If the general term formula of the known series is, then 420 is the _ _ _ _ item of the series.
16, and the point is on a straight line, then the value of is
17, distance from point (-2,-1) to straight line =
The equation of a circle whose center is point C (-3, 1) and whose radius is root number 5 is: (x+3)? + (y - 1)？ = 5
19, the real axis length of hyperbola is, the imaginary axis length is, and the eccentricity e is.
20. With points A( 1, 3) and B (-5, 1) as endpoints, the equation of the midline of the line segment is
Solution:
There are three steps to solve the midline equation of line segments with points A( 1, 3) and B (-5, 1) as endpoints.
One. First, find the linear equation where AB is located:
Let the linear equation of AB be y = KX+B.
Substitute a and b coordinates.
K+B=3
-5K+B= 1
K= 1/3，
Because the two straight lines are perpendicular, the product of k values is-1.
Therefore, the value of the median vertical line k is -3.
Second, find the midpoint coordinates of line segment AB:
The midpoint coordinates of AB are X=(-5+ 1)/2=-2, and Y=( 1+3)/2=2.
So the coordinates are (-2,2).
3. Finally, find the equation of the midline of the line segment with points A( 1, 3) and B (-5, 1) as endpoints:
Let the median vertical line be y =-3x+b.
Substitution (-2,2)
6+B=2，B=-4
So perpendicular bisector's equation is:
Y=-3X-4, which means 3X+Y+4=0.