Expansion Calculator for (a + b)^{n} :
The calculator given in this section can be used to find the expansions of algebraic expressions in the form
(a + b)^{n}
We can get the expansions of algebraic expressions in the above formula for any value of n.

To get expansion calculator for (a  b)^{n},
In this section, we are going to see, how to prove the expansions of algebraic identities geometrically.
Let us consider algebraic identity and its expansion given below.
(a + b)^{2} = a^{2} + 2ab + b^{2}
We can prove the the expansion of (a + b)^{2} using the area of a square as shown below.
(a + b)^{2} = a^{2} + 2ab + b^{2} (a + b)^{2} = (a  b)^{2} + 4ab  
(a  b)^{2} = a^{2}  2ab + b^{2} (a  b)^{2} = (a + b)^{2}  4ab  
a^{2}  b^{2} = (a + b)(a  b)  
(x + a)(x + b) = x^{2} + (a + b)x + ab 
Examples 
(a + b)^{3 }= a^{3 }+ 3a^{2}b + 3ab^{2 }+ b^{3} (a + b)^{3 }= a^{3 }+ 3ab(a + b)^{ }+ b^{3}  
(a  b)^{3 }= a^{3 } 3a^{2}b + 3ab^{2 } b^{3} (a  b)^{3 }= a^{3 } 3ab(a  b)^{ } b^{3}  
a^{3 }+ b^{3} = (a + b)(a^{2 } ab + b^{2}) a^{3 } b^{3} = (a  b)(a^{2 }+ ab + b^{2})  
a^{3 }+ b^{3} = (a + b)^{3}  3ab(a + b) a^{3 } b^{3} = (a  b)^{3} + 3ab(a  b) 
(15) (a+b+c)²= a²+b²+c² +2ab+2bc+2ca (16) (a+bc)²=a²+b²+c² +2ab2bc2ca (17) (ab+c)²= a²+b²+c²2ab2bc+2ca (18) (abc)²= a²+b²+c²2ab+2bc2ca (19) a² + b² = (a + b)²  2ab (20) a² + b² = (a  b)² + 2ab (21) a² + b²=½ [(a+b)²(ab)²] (22) ab = ¼[(a+b)² (a  b)²] 
(23) (a + b + c)³ = a³ + b³ + c³ + 3a²b + 3a²c + 3ab² + 3b²c + 3ac² + 3bc² + 6abc
(24) (a + b  c)³ = a³ + b³  c³ + 3a²b  3a²c + 3ab²  3b²c + 3ac² + 3bc²  6abc
(25) (a  b + c)³ = a³  b³ + c³  3a²b + 3a²c + 3ab² + 3b²c + 3ac²  3bc²  6abc
(26) (a  b  c)³ = a³  b³  c³  3a²b  3a²c + 3ab²  3b²c + 3ac²  3bc² + 6abc
We can remember algebraic identities expansions like
(a + b)^{2}, (a + b + c)^{2}, (a + b + c)^{3}
In the above identities, if one or more terms is negative, how can we remember the expansion ?
This question has been answered in the following three cases.
Case 1 :
For example, let us consider the identity of (a + b + c)^{2}
We can easily remember the expansion of (a + b + c)^{2}.
If c is negative, then we will have
(a + b  c)^{2}
How can we remember the expansion of (a + b  c)^{2} ?
It is very simple.
Let us consider the expansion of (a + b + c)^{2}_{.}
(a + b + c)^{2} = a^{2} + b^{2} + c^{2} + 2ab + 2bc + 2ca
In the terms of the expansion above, consider the terms in which we find "c".
They are c^{2}, bc, ca.
Even if we take negative sign for "c" in c^{2}, the sign of c^{2} will be positive. Because it has even power 2.
The terms bc, ca will be negative. Because both "b" and "a" are multiplied by "c" that is negative.
Finally, we have
(a + b  c)^{2} = a^{2} + b^{2} + c^{2} + 2ab  2bc  2ca
Case 2 :
In (a + b + c)^{2}, if "b" is negative, then we will have
(a  b + c)^{2}
How can we remember the expansion of (a  b + c)^{2} ?
It is very simple.
Let us consider the expansion of (a + b + c)^{2}_{.}
(a + b + c)^{2} = a^{2} + b^{2} + c^{2} + 2ab + 2bc + 2ca
In the terms of the expansion above, consider the terms in which we find "b".
They are b^{2}, ab, bc.
Even if we take negative sign for "b" in b^{2}, the sign of b^{2} will be positive. Because it has even power 2.
The terms ab, bc will be negative. Because both "a" and "c" are multiplied by "b" that is negative.
Finally, we have
(a  b + c)^{2} = a^{2} + b^{2} + c^{2}  2ab  2bc + 2ca
Case 3 :
In (a + b + c)^{2}, if both "b" and "c" are negative, then we will have
(a  b  c)^{2}
How can we remember the expansion of (a  b  c)^{2} ?
It is very simple.
Let us consider the expansion of (a + b + c)^{2}_{.}
(a + b + c)^{2} = a^{2} + b^{2} + c^{2} + 2ab + 2bc + 2ca
In the terms of the expansion above, consider the terms in which we find "b" and "c".
They are b^{2}, c^{2}, ab, bc, ac.
Even if we take negative sign for "b" in b^{2} and negative sign for "c" in c^{2}, the sign of both b^{2 }and c^{2} will be positive. Because they have even power 2.
The terms "ab" and "ca" will be negative.
Because, in "ab", "a" is multiplied by "b" that is negative.
Because, in "ca", "a" is multiplied by "c" that is negative.
The term "bc" will be positive.
Because, in "bc", both "b" and "c" are negative.
That is,
negative ⋅ negative = positive
Finally, we have
(a  b  c)^{2} = a^{2} + b^{2} + c^{2}  2ab + 2bc  2ca
In the same way, we can get idea to remember the the expansions of
(a + b  c)^{3}, (a  b + c)^{3}, (a  b  c)^{3}
After having gone through the stuff given above, we hope that the students would have understood the expansions of algebraic identities.
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