(a) I got 2x^2 - 9x + 4 = 0
(b) I can't do
(c) x = 1/2 or x = 4
For a)
Simply multiply through with $\displaystyle x $ and take all the terms over to the left hand side of the equal sign.
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For b)
$\displaystyle xy = 4 $ ----- (1)
$\displaystyle 2x^2 - 9x + 4 = 0 $
$\displaystyle -(2x^2 - 9x) = 4 $ ------- (2)
Set (1) = (2)
$\displaystyle -(2x^2 - 9x) = xy $
$\displaystyle y = -(2x - 9) $
$\displaystyle y = -2x + 9 $
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For c)
$\displaystyle 2x^2 - 9x + 4 = 0 $
$\displaystyle (2x - 1)(x - 4) = 0 $
$\displaystyle x = \frac{1}{2} \ or \ x = 4 $