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Which of these is NOT a quadratic equation?

Class 10Standard Form and RootsQuadratic Equations

A $x^{2} - 1 = 0$
B $3 x^{2} + 2 x = 7$
C $x^{2} + \frac{1}{x} = 5$
D $5 x^{2} = 0$

Step-by-Step Solution

x^{2} + \frac{1}{x} = 5

has a term

\frac{1}{x}

, so multiplying by

x

gives

x^{3} + 1 = 5 x

, a cubic. It is not quadratic.

Answer: C)

x^{2} + \frac{1}{x} = 5

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