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Is this -4/(9(2x-4))=48? Or (-4/9)(2x-4)=48?

We can find the answers to both questions. Let's take the first interpretation first and see what we get.

To solve it we need to get rid of the fraction. In all questions of this type we take the denominator of the fraction (the bottom bit), and multiply both sides of the equation by it, which is the same as taking it across the equals sign from left, where it was a divisor over to the right, where it becomes a multiplier. So we get -4=48*9(2x-4). We have the unknown x inside the brackets, so we have to get it out into the open by multiplying what's outside by everything in the brackets. That gives us -4=864x-1728. Already this looks like the wrong interpretation of the question because the numbers are big and clumsy. But we'll carry on. The next thing to do is get the knowns (ordinary numbers) on one side of the equals and the unknowns on the other. So -1728 on the right becomes +1728 when we take it across to the left (because the equals sign changes + to - and - to +, multiply to divide and divide to multiply). When we add 1728 to -4 it's the same as subtracting 4 from 1728, so we get 1724=864x. So we take 864 from right to left (changing multiply to divide as we move it) and we get 1724/864=x, which gives us a horrible 431/216 or 1.995 approx. seems unlikely then that this was the intended question.

Let's go for the other interpretation: (-4/9)(2x-4)=48. One thing to notice (which also applied to the first interpretation) is that  the equation can be simplified by dividing both sides by 4. So (-1/9)(2x-4)=12. The only fraction we have is -1/9, so we just need to take the 9 across to the right where it multiplies 12. Therefore -(2x-4)=108. We can simplify this because 2 divides into both sides of the equation. So we get -(x-2)=54.  We can take the brackets with the minus sign over to the other side of the equation where the minus will become plus. So we get 0=54+x-2. Now we separate the knowns from the unknowns. -54+2=x. So x=-52. This looks more like the correct interpretation.

by Top Rated User (1.2m points)

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