If \(x=3\) is a root of the equation \(2x^2+qx-15=0\), what is the value of \(q\)?
Answer and explanation
Correct answer: -1
Substitute the given root into the equation: \(2(3)^2+q(3)-15=0\) ⇒ \(18+3q-15=0\) ⇒ \(3+3q=0\) ⇒ \(q=-1\). Option A (1) often arises from a sign mistake when moving terms; options C and D come from arithmetic or sign errors. Exam tip: always substitute the root first and simplify step by step, checking basic addition/subtraction carefully.
Frequently asked questions
What is the correct answer to this question?
-1
Why is this the correct answer?
Substitute the given root into the equation: \(2(3)^2+q(3)-15=0\) ⇒ \(18+3q-15=0\) ⇒ \(3+3q=0\) ⇒ \(q=-1\). Option A (1) often arises from a sign mistake when moving terms; options C and D come from arithmetic or sign errors. Exam tip: always substitute the root first and simplify step by step, checking basic addition/subtraction carefully.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Quadratic Equations. Topic: Introduction to Quadratic Equations.
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