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4x + 3 = 2x + 8. What is the solution to the given equation? (type…

Step by step, with the reason for every step · SAT: Linear equations in one variable · SAT Math

Step by step

The question

Question: solve 4x + 3 = 2x + 8.

4x + 3 = 2x + 8

1 Get x on one side

There is x on both sides.

We want x on one side only.

The numbers in front of x are 2 and 4.

We remove the smaller one, 2x.

Then the x part that is left is plus.

A plus x part is easier to work with.

So we remove the 2x from the right side.

To remove 2x, we take away 2x.

We do it on both sides.

Why both sides?

The = sign means both sides are the same amount.

If we change only one side, they are not the same any more.

4x + 3 − 2x = 2x + 8 − 2x

2x and − 2x make zero.

Cross them out.

4x − 2x = 2x.

4x − 2x = 2x

Now we have 2x + 3 = 8.

2x + 3 = 8

We want x by itself.

Two things are stuck to x: times 2 and + 3.

First x was times 2.

Then + 3.

To take them off, we go backwards.

First we remove the + 3.

Then the times 2.

x → × 2 → + 3
take off: − 3, then ÷ 2

2 Remove the + 3

To remove + 3, we take away 3.

We do it on both sides, so they stay equal.

2x + 3 − 3 = 8 − 3

+ 3 and − 3 make zero.

Cross them out.

8 − 3 = 5.

8 − 3 = 5

Now we have 2x = 5.

2x = 5

3 Remove the 2

2x means 2 times x.

We want just x.

To remove times 2, we divide by 2.

We do it on both sides, so they stay equal.

2x2 = 52

2 divided by 2 is 1.

So just x is left.

So x = 5/2!

x = 52

4 Check

Let's check: put 5/2 in place of x.

First the left side.

Left: 4(52) + 3 = 202 + 3 = 10 + 3 = 13

Now the right side.

Right: 2(52) + 8 = 102 + 8 = 5 + 8 = 13

Both sides are 13.

So x = 5/2 is right!

Both sides equal 13

5 Type it in

The answer box takes 5 characters.

5/2 has 3.

It fits.

5/2: 3 characters, up to 5 fit

We type 5/2.

Let's look back.

First: get x on one side.

Then: remove the + 3.

Then: remove the 2.

Then: check.

Last: type it in.

Answer
x = 52

Your turn

Try this one yourself, then check:

Solve 8x + 7 = 3x + 13
Show the answer
x = 65

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