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Algebraic Manipulation: Squares & Corollaries

Formula #1: (a+b)2 = a2 + 2ab + b2​ 

Proof: (a+b)2​ = (a+b)(a+b) = a(a+b) + b(a+b) = a2​ + ab + ab + b2​ = a2​ + 2ab + b2​ 

Problem 1.1: Find the square of 3a + 5b using formula.
Solution: (3a + 5b)2 = (3a)2 + 2 × 3a × 5b + (5b)2 = 9a2 + 30ab + 25b2 

Problem 1.2: Find the square of 105 using formula.
Solution: (105)2 = (100 + 5)2

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Formula #2: (a-b)2 = a2 - 2ab + b2​ 

Proof: (a-b)2​ = (a-b)(a-b) = a(a-b) - b(a-b) = a2​ - ab - ab + b2​ = a2​ - 2ab + b2​ 

Problem 2.1: Find the square of 3p-2q using formula.
Solution: 

Problem 2.2: Find the square of -x-y using formula.
Solution:

Problem 2.3: Find the square of 97 using formula.
Solution: (97)2 = (100-3)2 

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So far, we learned to use the two most basic formula's of squaring using two term expressions. Now, lets use these formula's to square expressions having three terms.

Problem 3.1: Find the square of a+b+c using formula.

Problem 3.2: Find the square of a-b-c using formula.

Problem 3.3: Find the square of a-b+c using formula.

Problem 3.4: Find the square of a+b-c using formula.