$$-5x = 5$$
to get $x$ on its own, does the minus sign cancel when it goes underneath the line?
like $x = 5/5$ or is it $x = -5/5$
Sorry I really can't remember this stuff...
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The latter, you are dividing by $-5$, the the result is $-1$. To check it, plug $x=-1$ into the original and see if the LHS = RHS. – Amzoti Dec 16 '13 at 13:21
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alright so it is -1, that's what I thought – user2387699 Dec 16 '13 at 13:22
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Don't try to remember rules specific to the minus sign. The important thing to remember for this type of algebraic manipulation is that you will always be performing the exact same operation to both sides of the equation. As long as you stick to that rule, you'll do fine.
If you want to isolate the x then you'll need to divide both sides by -5 (or first divide by 5, giving you -x=1, then either divide or multiply both sides by -1) to get x=1
Sparr
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$-5x=5\Leftrightarrow -\frac{1}{5}\times (-5x)= -\frac{1}{5} \times 5\Leftrightarrow x=-1.$
Avitus
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$$\color{red}{-5}\times x=5$$ We want to get rid of $\color{red}{-5}$, so we will multiply both sides of the equations by its inverse which is: $$\dfrac{1}{\color{red}{-5}}=\color{blue}{-\dfrac{1}{5}}$$ So: $$\color{blue}{-\dfrac{1}{5}}\times\color{red}{-5}\times x=5\times \color{blue}{-\dfrac{1}{5}}\implies x=-\dfrac{5}{5}=-1$$ $$\,\,\therefore\,\,x=-1$$