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Question 63780: y=-2x^2-16x-35
find the vertex
find the equation of the axis of symetry
find the coordinates of the focus
find the equation of the directrix
find the length of the latus rectum
Answer by venugopalramana(3286)   (Show Source):
You can put this solution on YOUR website! SEE THE FOLLOWING EXAMPLE AND TRY.IF STILL IN DIFFICULTY PLEASE COME BACK
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(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
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