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Solve 6/(x + 1) = 2 + 3/(x + 1)

Step by step, with the reason for every step · Rational equations · Algebra 2

Step by step

The question

Question: solve 6/(x + 1) = 2 + 3/(x + 1).

6x + 1 = 2 + 3x + 1

First: a bottom can never be 0.

x = −1 makes x + 1 0.

So x ≠ −1.

x ≠ −1

1 Remove the fractions

The bottom is (x + 1).

Times (x + 1) will remove it.

We multiply every part by (x + 1).

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

(x + 1) × 6x + 1 = (x + 1) × 2 + (x + 1) × 3x + 1

(x + 1) divided by (x + 1) is 1.

(x + 1) times 2 is 2(x + 1).

(x + 1) divided by (x + 1) is 1.

Write what is left.

No more fractions!

6 = 2(x + 1) + 3

2 Open the brackets

The 2 in front of the bracket multiplies every part inside.

So we write 2 times each part.

6 = 2 × x + 2 × 1 + 3

Work out each multiplication.

6 = 2x + 2 + 3

3 Group like terms

Terms are the parts between the + and − signs.

Like terms are the same kind: same letters, same powers.

Plain numbers go together.

2 + 3 = 5.

2 + 3 = 5

Now we have 6 = 2x + 5.

6 = 2x + 5

Let's swap the two sides, so x is on the left.

2x + 5 = 6

We want x by itself.

Two things are stuck to x: times 2 and + 5.

The + 5 is on the outside, so it comes off first.

Then the times 2.

4 Remove the + 5

To remove + 5, we take away 5.

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

2x + 5 − 5 = 6 − 5

+ 5 and − 5 make zero.

Cross them out.

6 − 5 = 1.

6 − 5 = 1

Now we have 2x = 1.

2x = 1

5 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 = 12

2 divided by 2 is 1.

So just x is left.

So x = 1/2!

x = 12

6 Check

Let's check: put 1/2 in place of x.

First the left side.

Left: 612 + 1 = 632 = 4

Now the right side.

Right: 2 + 312 + 1 = 2 + 332 = 2 + 2 = 4

Both sides are 4.

So x = 1/2 is right!

Both sides equal 4

Let's look back.

First: remove the fractions.

Then: open the brackets.

Then: group like terms.

Then: remove the + 5.

Then: remove the 2.

Last: check.

Answer
x = 12

Your turn

Try this one yourself, then check:

9x + 1 = 2 + 1x + 1
Show the answer
x = 3

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