Question 63653
Hello, I'm Alex. Could I please ask your assistance on these two Homeschool American School Problems because I don't have a teacher here to help? 
(1) What is the equation of the perpendicular bisector of the line between points A(2,2)=(X1,Y1) and B(6, 6)=(X2,Y2)? 
PERPENDICULAR BISECTOR OF AB GOES THROUGH MIDPOINT OF AB.....SAY C AND IS 
PERPENDICULAR TO AB.
COORDINATES OF C = [(X1+X2)/2,(Y1+Y2)/2] = [(2+6)/2,(2+6)/2=(4,4)= (X',Y')
SLOPE OF AB = (Y2-Y1)/(X2-X1)= (6-2)/(6-2)=4/4=1
HENCE SLOPE OF ITS PERPENDICULAR = -1/1 = -1 = M [PRODUCT OF SLOPES OF  2 PERPENDICULAR LINES =-1]
HENCE EQN. OF PERPENDICULAR BISECTOR IS
Y-Y'=M(X-X')
Y-4=-1(X-4)=-X+4
Y=-X+8

(2) What is the (a)directrix and the (b)focus of the parabola y = x^2 - 5x + 4?
Y = [X^2-2*X*(5/2)+(5/2)^2]-(5/2)^2+4
(X-2.5)^2 = (Y+2.25)
COMPARING WITH STD. EQN. OF PARABOLA
(X-H)^2 = 4A(Y-K)
4A=1......A=1/4=0.25
VERTEX = (H,K)......= (2.5,-2.25)
AXIS = X-H=0.......X-2.5=0
FOCUS = [H,K+A].....[2.5,-2.25+0.25]=(2.5,-2)
DIRECTRIX = Y-K+A=0......Y+2.25+0.25=0.......Y+2.5=0