How do you find the square of a sum?

Question

Lets use the example (a+b)^2

How would you find the square of the sum?

Answer 1

(a+b)(a+b)

= a² + 2ab + b²

Answer 2

FOIL: (a + b)(a + b) = a^2 + 2ab + b^2

Answer 3

you would use foil - which means first outer inner and last. anytime you are squaring something it is just that mulitped by itself.

so it would be (a+b)(a+b)

so then use foil by doing aXa you get a sqaurded, then outer would be aXb youd get ab, then inner bXa youd get ba (also it could be ab.. ba and ab are the same thing) then last would b e bXb which is b sqaurded. so you get a sqaurderd then 2ab then b sqaurded. theres your answer! hope this helped  

Answer 4

The first answer is correct.  By the way, FOIL stand for first, outside, inside, last.  In other words write it as (a+b)(a+b) then do the first number/variable and so on, putting a '+' between each.

Answer 5

If A and B are constants, you can add inside the parentheses and then square the sum. For an example, let A=2 and B=3.

(2+3)² = (5)² = 25

Does that make sense?

If A and B are just variables, you can use the FOIL (First, Outer, Inner, Last) method to multiply (A+B)(A+B).

AA+BA+BA+BB or A²+2BA+B²

Answer 6

Just multiply it out:

(a + b) * (a + b)

= a(a + b) + b(a+ b)

= a^2 + ab + ba +b^2

= a^2 + 2ab + b^2

Answer 7

If FOIL  confuses you just remember to take each term of the first factor and multiply them one at a time by the second factor's terms.

(a+b)(a+b) = a^2+ab+ba+b^2

Then add like terms.

Since ab and ba are the same but rearranged they can be added to get:

a^2+2ab+b^2

This works for any factoring problem, eg

(a+b)(c+d) = ac+ad+bc+bd using the distributive property.