Friday

October 9, 2015
Posted by **Anamika** on Sunday, January 6, 2013 at 6:30am.

y= x^2-2x-3

Find:

a)Vertex:

b)Axis:

c)Focus:

d)Directrix:

e)Latus Rectum:

- maths -
**Henry**, Sunday, January 6, 2013 at 12:53pmY = x^2-2x-3.

a. h = Xv = -B/2A = 2/2 = 1.

K = Yv = 1^2-2*1-3 = -4.

V = (h,k) = (1,-4).

b. Axis: X = h = 1.

c. D(1,Y1), V(1,-4), F(1,Y2).

VF = Y2-(-4) = Y2+4 = 1/4a = 1/4.

Y2+4 = 1/4.

Y2 = 1/4-4 = 1/4-16/4 = -15/4.

d. DV = -4-Y1 = 1/4a = 1/4.

-4-Y1 = 1/4

-Y1 = 1/4+4 = 1/4+16/4 = 17/4.

Y1 = -17/4.

- maths -
**Henry**, Sunday, January 6, 2013 at 3:11pme. A(x1,-15/4), F(1,-15/4), B(x2,-15/4).

AF = 1-x1 = 1/2a = 1/2.

1-x1 = 1/2.

-x1 = 1/2-1 = -1/2

X1 = 1/2.

FB = x2-1 = 1/2a = 1/2.

X2 = 1/2+1 = 3/2.

NOTE: The Latus Rectum for the y-parabola is a hor. line that passes through the focus.