What is the constant term in \( (x-9)^2 \)?
Answer and explanation
Correct answer: 81
Using the identity \((a-b)^2=a^2-2ab+b^2\), we get \((x-9)^2=x^2-18x+81\). A constant term has no variable, so the constant term is 81. The term \(-18x\) contains x and is therefore not constant. Exam tip: in the square of a binomial, the final constant term is the square of the constant part.
Frequently asked questions
What is the correct answer to this question?
81
Why is this the correct answer?
Using the identity \((a-b)^2=a^2-2ab+b^2\), we get \((x-9)^2=x^2-18x+81\). A constant term has no variable, so the constant term is 81. The term \(-18x\) contains x and is therefore not constant. Exam tip: in the square of a binomial, the final constant term is the square of the constant part.
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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