AlgebraEasy
Expand (x + 3)²
Expand a squared binomial without losing its middle term.
Method: Square-of-a-sum identity
Step-by-step solution
- 1
Write the product
A square means multiplying the binomial by itself.
- 2
Distribute
Multiply each term in the first binomial by each term in the second.
- 3
Combine like terms
The two 3x terms add to 6x.
Final answer
This is the identity (a+b)²=a²+2ab+b² with a=x and b=3.
Common mistake
Writing x²+9 omits the middle term 2·x·3.
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