What is the coefficient of (x) in ( (3x-4)(3x+7) )?
Answer and explanation
Correct answer: 9
Expanding the expression,
a(3x-4)(3x+7)=9x^2+21x-12x-28=9x^2+9x-28.
Therefore, the coefficient of (x) is 9. Here, 21 is the coefficient from only one cross-term; the other cross-term, −12x, must also be combined. Exam tip: After multiplying two binomials, always combine like terms.
Frequently asked questions
What is the correct answer to this question?
9
Why is this the correct answer?
Expanding the expression,
a(3x-4)(3x+7)=9x^2+21x-12x-28=9x^2+9x-28.
Therefore, the coefficient of (x) is 9. Here, 21 is the coefficient from only one cross-term; the other cross-term, −12x, must also be combined. Exam tip: After multiplying two binomials, always 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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