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Simplify the following expression: 1.685.32×5.32−3.64×3.64
8.99
8.96
8.94
8.86
8.96
Recognize the numerator as a difference of squares a2−b2 where a=5.32 and b=3.64. Since a−b=5.32−3.64=1.68, the expression simplifies instantly to a+b=5.32+3.64=8.96.
Expression to simplify: (5.32 × 5.32 - 3.64 × 3.64) / 1.68
a2−b2=(a−b)(a+b)
Recognize the numerator as a difference of squares a2−b2 where a=5.32 and b=3.64. Since a−b=5.32−3.64=1.68, the expression simplifies instantly to a+b=5.32+3.64=8.96.
Many students attempt to calculate 5.32×5.32 and 3.64×3.64 individually, which is time-consuming and prone to decimal calculation errors.
Identify the algebraic form
The numerator is in the form a2−b2, where a=5.32 and b=3.64.
a2−b2=(5.32)2−(3.64)2
Apply algebraic identity
Using the formula a2−b2=(a−b)(a+b), rewrite the numerator.
(5.32−3.64)(5.32+3.64)
Simplify and divide
Calculate the difference 5.32−3.64=1.68. The expression becomes 1.681.68×(5.32+3.64). The 1.68 terms cancel out.
5.32+3.64=8.96
B is correct because the result of the simplification 5.32+3.64 equals 8.96.
This type of simplification is common in 'Quantitative Aptitude' to test recognition of algebraic identities instead of rote computation; always look for patterns like a2−b2 or a2+2ab+b2 first.