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The equation of directrix is to the parabola ` 4x ^ 2 - 4x - 2y + 3 = 0 ` will beA. `2y = 1 `B. ` 2x = 1 `C. `2y = 3 `D. ` 2x = 3 ` |
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Answer» Correct Answer - A Given parabola , ` 4x ^ 2 - 4x - 2y + 3= 0 ` ` rArr 4 ( x ^ 2 - x ) = 2y - 3 ` ` rArr 4 ( x ^ 2 - x + ( 1 ) /( 4 ) - ( 1 )/( 4 )) = 2y - 3 ` ` rArr ( x - ( 1 ) /( 2 ) ) ^ 2 = 2y - 2 ` ` rArr ( x - (1 ) /(2 ) ) ^ 2 = 2 ( y -1 ) ` Which is of form ` X^ 2 = 4aY ` where , ` X = x - (1 ) / ( 2 ) and Y = y - 1 ` and ` a = (1 )/ ( 2 ) ` ` therefore ` Directrix, ` Y + a = 0 ` ` rArr y - 1 + ( 1 ) / ( 2 ) = 0 ` ` rArr y - ( 1 ) / ( 2 ) = 0 ` ` rArr 2y = 1 ` |
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