Step by step
The question
Question: simplify 2x² + 3x − x² + 4.
Simplify means: write it shorter, with the same value.
2x2 + 3x − x2 + 4
1 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.
like terms = same letters,
same powers
We move like terms next to each other.
Each term takes its sign with it.
= 2x2 − x2 + 3x + 4
2x² − x² is x².
It is like 2 apples take away 1 apple: that is 1 apple.
2x2 − x2 = x2
So the expression is x² + 3x + 4.
= x2 + 3x + 4
2 Check
Let's check.
We pick a number for each letter: x = 2.
We put it into the start.
Start: 2 × 22 + 3 × 2 − 22 + 4
= 8 + 6 − 4 + 4 = 14
Now into our answer.
Answer: 22 + 3 × 2 + 4 = 4 + 6 + 4 = 14
Both give 14.
Same value, so x² + 3x + 4 is right!
Both give 14
Let's look back.
First: group like terms.
Last: check.
Answer
= x2 + 3x + 4