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Simplify ( (2a+3)(2a-3) ).
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Answer and explanation
Correct answer: \(4a^2-9\)
This expression has the form \((p+q)(p-q)=p^2-q^2\). Here, \(p=2a\) and \(q=3\), so \((2a+3)(2a-3)=(2a)^2-3^2=4a^2-9\). Option A incorrectly adds the two squares. Exam tip: for conjugate binomials, the middle terms cancel, leaving the difference of the squares.
Frequently asked questions
What is the correct answer to this question?
\(4a^2-9\)
Why is this the correct answer?
This expression has the form \((p+q)(p-q)=p^2-q^2\). Here, \(p=2a\) and \(q=3\), so \((2a+3)(2a-3)=(2a)^2-3^2=4a^2-9\). Option A incorrectly adds the two squares. Exam tip: for conjugate binomials, the middle terms cancel, leaving the difference of the squares.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Exploring Algebraic Identities. Topic: Algebraic identities.
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