# Square of a Sum (a + b)^{2}

How to solve the square of a sum (a + b)^2: formula, 1 example, and its solution.

## Formula

### Formula

(a + b)^{2} = a^{2} + 2ab + b^{2}

The middle sign in (a + b)^{2} is plus.

So the middle term of the right side, +2ab, is also plus.

This is the difference between

the (a + b)^{2} formula and the (a - b)^{2} formula.

## Example

### Example

### Solution

First square the first term: x^{2}.

The middle sign in (x + 3)^{2} is plus.

So write

+2 times,

the first term, x times,

the last term, 3.

Square the last term: +3^{2}.

So (x + 3)^{2} = x^{2} + 2⋅x⋅3 + 3^{2}.

+2⋅x⋅3 = +6x

+3^{2} = +9

So x^{2} + 6x + 9 is the answer.