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45 votes
2x + 8 = 10

So I know we subtract 8 on both sides do the equation but would we be able to do 10 also or no? I’m confused on how we know which number to use to make the equation make more sense..?

User Douwe Maan
by
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1 Answer

5 votes
5 votes

Answer:

Subtract 8 from both sides.

Divide both sides by 2.

Explanation:

Here is an explanation.

In order to isolate the variable x, or solve for x, you need to undo the operations that are being done to x. To undo an operation, you must do the opposite operation.

The opposite of addition is subtraction.

Since 8 is being added to 2x, and you want to undo the addition of 8, you subtract 8. The rule is that you must do the same operation to both sides of the equation, so to get rid of the + 8 on the left side, you must do - 8 on both sides, like this:

2x + 8 = 10

2x + 8 - 8 = 10 - 8

2x = 2

By subtracting 8 from both sides, we got rid of the addition of 8 on the left side.

2x = 2

Now we have 2x. We want x alone. What operation is there between the 2 and the x in 2x? 2x means 2 times x. 2x is a multiplication. The opposite of multiplication is division. To undo the multiplication of x by 2, you need to divide the left side by 2. A division cancels out a multiplication. Once again, the rule is that you must do the same operation to both sides, so you must divide both sides by 2.

2x = 2

2x/2 = 2/2

x = 1

I hop that helps. If you have questions, just ask.