Simplify 2(x^2 + 3x) - x(x - 1)

Step by step

The question

Question: simplify 2(x² + 3x) − x(x − 1).

Simplify means: write it shorter, with the same value.

1 Open the brackets

What is in front of a bracket multiplies every part inside.

So we write each part times what is in front.

Watch the signs.

2 times x² is 2x².

2 times 3x is 6x.

(−x) times x is −x².

(−x) times (−1) is x.

2 Group like terms

Terms are the parts between the + and − signs.

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

All the x² terms go together.

Each colour is one kind.

We move like terms next to each other.

Each term takes its sign with it.

2x² − x² is x².

It is like 2 apples take away 1 apple: that is 1 apple.

6x + x is 7x.

So the expression is x² + 7x.

3 Check

Let's check.

We pick a number for each letter: x = 2.

We put it into the start.

Now into our answer.

Both give 18.

Same value, so x² + 7x is right!

Let's look back.

First: open the brackets.

Then: group like terms.

Last: check.