In ( (x+3)^2=x^2+6x+9 ), where did (9) come from?
Answer and explanation
Correct answer: \(3^2\)
In the identity \((a+b)^2=a^2+2ab+b^2\), the last term is \(b^2\). Here, \(a=x\) and \(b=3\), so the last term is \(3^2=9\). The term \(2\cdot x\cdot3=6x\) gives the middle term, not 9. Exam tip: in a square identity, the square of the second term gives the last term.
Frequently asked questions
What is the correct answer to this question?
\(3^2\)
Why is this the correct answer?
In the identity \((a+b)^2=a^2+2ab+b^2\), the last term is \(b^2\). Here, \(a=x\) and \(b=3\), so the last term is \(3^2=9\). The term \(2\cdot x\cdot3=6x\) gives the middle term, not 9. Exam tip: in a square identity, the square of the second term gives the last term.
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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