Given that $x=-2 $and $ y=4 $ evaluate each of the following expressions.
a) $ 5 y-4 x $
b) $\frac{1}{x}-y+3$
Given: $x = -2 y = 4$
To do: Solve a) and b)
Solution:
a) $ 5y - 4x$
Substitute the values of $x$ and $y$ in $5y - 4x$
$5 (4) - 4 (-2) = 20 - (-8)$
= $20 + 8$
= $28$
So, the answer is 28.
b)$ \frac{1}{x} - y + 3$
Substitute the values of $x$ and $y$
$ \frac{1}{-2} - 4 + 3 = \frac{-1}{ 2} - 1$
= $\frac{-3}{ 2}$
So, the answer is $\frac{-3}{2}$
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