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Which of these is a quadratic equation in the variable $x$ ?

Class 10Standard Form and RootsQuadratic Equations

A $(x - 1) (x + 1) = x^{2}$
B $2 x + 7 = 0$
C $(x + 2) (x - 3) = 0$
D $x^{3} - 1 = 0$

Step-by-Step Solution

(x + 2) (x - 3) = 0

expands to

x^{2} - x - 6 = 0

, a quadratic.

(x - 1) (x + 1) = x^{2}

reduces to -1=0 (no

x^{2}) .2 x + 7 = 0

is linear;

x^{3} - 1

is cubic.

Answer: C)

(x + 2) (x - 3) = 0

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