Steply

Solve 3^x + 2 = 29

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

Step by step

The question

Question: solve 3 to the power x, + 2 = 29.

x is up in the power.

3x + 2 = 29

1 Get the power alone

First the power must be alone: nothing added to it, nothing times it.

first: the power alone

We want the power by itself.

The + 2 is in the way.

To remove + 2, we take away 2.

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.

3x + 2 − 2 = 29 − 2

+ 2 and − 2 make zero.

Cross them out.

29 − 2 is 27.

Now we have 3ˣ = 27.

3x = 27

2 Write 27 as a power of 3

27 is 3 times itself, 3 times.

3 × 3 × 3 = 27

So 27 is 3³.

Now both sides are 3 to a power.

3x = 33

3 The powers are equal

Both sides are 3 to a power.

Same base, and they are equal.

So the powers must be equal too.

same base → same power

So x = 3!

x = 3

4 Check

Let's check in the question: put 3 in place of x.

Check: 33 + 2 = 27 + 2 = 29

We get 29, the same as the right side.

So x = 3 is right!

Let's look back.

First: get the power alone.

Then: write 27 as a power of 3.

Then: the powers are equal.

Last: check.

Answer
x = 3

Your turn

Try this one yourself, then check:

Solve 3x + 4 = 31
Show the answer
x = 3

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