Solve 7 = 2k + 1

Step by step

The question

Question: solve 7 = 2k + 1.

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

We want k by itself.

Two things are stuck to k: times 2 and + 1.

The + 1 is on the outside, so it comes off first.

Then the times 2.

1 Remove the + 1

To remove + 1, we take away 1.

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.

+ 1 and − 1 make zero.

Cross them out.

7 − 1 = 6.

Now we have 2k = 6.

2 Remove the 2

2k means 2 times k.

We want just k.

To remove times 2, we divide by 2.

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

2 divided by 2 is 1.

So just k is left.

6 divided by 2 is 3.

So k = 3!

3 Check

Let's check: put 3 in place of k.

First the left side.

Now the right side.

Both sides are 7.

So k = 3 is right!

Let's look back.

First: remove the + 1.

Then: remove the 2.

Last: check.