What is the expansion of \((4x+5)(x-3)\)?
Answer and explanation
Correct answer: \(4x^2-7x-15\)
Apply the distributive property: \((4x+5)(x-3)=4x\cdot x+4x\cdot(-3)+5\cdot x+5\cdot(-3)\). This gives \(4x^2-12x+5x-15=4x^2-7x-15\), so option A is correct. In option B, the middle terms \(-12x+5x\) have been combined with the wrong sign. In an exam, check the signs of the two middle terms carefully.
Frequently asked questions
What is the correct answer to this question?
\(4x^2-7x-15\)
Why is this the correct answer?
Apply the distributive property: \((4x+5)(x-3)=4x\cdot x+4x\cdot(-3)+5\cdot x+5\cdot(-3)\). This gives \(4x^2-12x+5x-15=4x^2-7x-15\), so option A is correct. In option B, the middle terms \(-12x+5x\) have been combined with the wrong sign. In an exam, check the signs of the two middle terms carefully.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Polynomials. Topic: Operations on real numbers and the laws of exponents.
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