Which of the following is a pure quadratic equation?
Answer and explanation
Correct answer: \(4x^2-9=0\)
A pure quadratic equation has the form \(ax^2+bx+c=0\) with the linear coefficient \(b=0\), so it reduces to \(ax^2+c=0\). In \(4x^2-9=0\) there is no \(x\) term, so it is a pure quadratic. The closest distractor, \(x^2+2x+1=0\), is a quadratic but not pure because of the \(2x\) term. Exam tip: check the coefficient of \(x\); if it is zero (or the \(x\) term is absent) the equation is a pure quadratic.
Frequently asked questions
What is the correct answer to this question?
\(4x^2-9=0\)
Why is this the correct answer?
A pure quadratic equation has the form \(ax^2+bx+c=0\) with the linear coefficient \(b=0\), so it reduces to \(ax^2+c=0\). In \(4x^2-9=0\) there is no \(x\) term, so it is a pure quadratic. The closest distractor, \(x^2+2x+1=0\), is a quadratic but not pure because of the \(2x\) term. Exam tip: check the coefficient of \(x\); if it is zero (or the \(x\) term is absent) the equation is a pure quadratic.
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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