When first applying ( (x+1)(x+3) ) in ( (x+1)(x+2)(x+3) ), what form is obtained?
Answer and explanation
Correct answer: \(x^2+4x+3\)
First multiply the outer factors: \((x+1)(x+3)=x^2+3x+x+3=x^2+4x+3\). Therefore, the required form is \(x^2+4x+3\). In \(x^2+2x+3\), the middle terms \(3x\) and \(x\) have not been added correctly. Exam tip: while multiplying two binomials, write all four products and then combine like terms.
Frequently asked questions
What is the correct answer to this question?
\(x^2+4x+3\)
Why is this the correct answer?
First multiply the outer factors: \((x+1)(x+3)=x^2+3x+x+3=x^2+4x+3\). Therefore, the required form is \(x^2+4x+3\). In \(x^2+2x+3\), the middle terms \(3x\) and \(x\) have not been added correctly. Exam tip: while multiplying two binomials, write all four products and then combine like terms.
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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