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Are 6(x + 3) - 4 and 6x + 14 equivalent

Step by step, with the reason for every step · Equivalent expressions · Algebra 1

Step by step

The question

Question: are 6(x + 3) − 4 and 6x + 14 equivalent?

6(x + 3) − 4 and 6x + 14

Equivalent means: the two are equal, whatever number the letter is.

equivalent = equal for every number

First we simplify the first one: 6(x + 3) − 4.

We write it shorter, with the same value.

= 6(x + 3) − 4

1 Open the brackets

The 6 in front of the bracket multiplies every part inside.

a(b + c) = ab + ac

So we write 6 times each part.

= 6(x) + 6(3) − 4

6 times x is 6x.

6 times 3 is 18.

= 6x + 18 − 4

2 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.

Each colour is one kind.

like terms = same letters,
same powers

18 − 4 is 14.

18 − 4 = 14

So the expression is 6x + 14.

= 6x + 14

3 Compare

Now both are 6x + 14.

The same terms.

= 6x + 14 = 6x + 14

So yes: they are equivalent.

= yes: equivalent

4 Check

Let's check with a number: x = 2.

The first gives 26.

The second gives 26.

The same.

So the answer is right!

x = 2: 6(2 + 3) − 4 = 26, 6(2) + 14 = 26

Let's look back.

First: open the brackets.

Then: group like terms.

Then: compare.

Last: check.

Answer
= yes: equivalent

Your turn

Try this one yourself, then check:

Are 4(x + 3) − 3 and 4x + 9
Show the answer
yes, equivalent

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