What is the expansion of ((3x-1)(x+4))?
Answer and explanation
Correct answer: \(3x^2+11x-4\)
Using the distributive property, \((3x-1)(x+4)=3x\cdot x+3x\cdot4-1\cdot x-1\cdot4=3x^2+12x-x-4=3x^2+11x-4\). Therefore, option D is correct. In option A, \(12x-x\) has incorrectly been simplified to \(x\). Exam tip: after expanding, check the sign of every product before combining like terms.
Frequently asked questions
What is the correct answer to this question?
\(3x^2+11x-4\)
Why is this the correct answer?
Using the distributive property, \((3x-1)(x+4)=3x\cdot x+3x\cdot4-1\cdot x-1\cdot4=3x^2+12x-x-4=3x^2+11x-4\). Therefore, option D is correct. In option A, \(12x-x\) has incorrectly been simplified to \(x\). Exam tip: after expanding, check the sign of every product before combining like terms.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Exploring Algebraic Identities. Topic: Quadratic expressions.
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