Step by step
The question
Question: simplify x(x + 4).
Simplify means: write it shorter, with the same value.
x(x + 4)
1 Open the brackets
The x in front of the bracket multiplies every part inside.
a(b + c) = ab + ac
So we write x times each part.
= x(x) + x(4)
x times x is x².
x times 4 is 4x.
= x2 + 4x
2 Check
Let's check.
We pick a number for each letter: x = 2.
We put it into the start.
Start: 2 × (2 + 4) = 2 × 6 = 12
Now into our answer.
Answer: 22 + 4 × 2 = 4 + 8 = 12
Both give 12.
Same value, so x² + 4x is right!
Both give 12
Let's look back.
First: open the brackets.
Last: check.
Answer
= x2 + 4x