Question

Which of the following is not a quadratic equation
(a) x² + 3x – 5 = 0
(b) x² + x3 + 2 = 0
(c) 3 + x + x² = 0
(d) x² – 9 = 0​

Answer 1

$\huge\pink {\underline{\mathbb {answer}}}$

$(b) \: {x}^{2} + {x}^{3} + 2 = 0$

this equation is not a quadratic equation because x3 is coming here which comes in cubic equation not in quadratic equation.

Answer 2

$\tt ☄♏GIVEN:-$

$\tt4 \: eq.$

$\tt ☄♍FIND:-$

$\tt which \: one \: is \: not \: a \: quadratic \: eq.$

$\tt ☄♓SOLUTION:-$

$\tt(note\ratio we \: know \: an \: eq. \: is \: said \: to \\ \tt be \: quadrtic \: when \: its \: degree \: is \: 2)$

$\tt(a) {x}^{2} - 3x - 5 = 0$

$\tt \: highest \: power \: is2 \: so \: degree \: is \\ \tt also2$

$\tt \therefore it \: is \: a \: quadratic \: eq.$

$\tt(b) {x}^{2} + {x}^{3} + 2= 0$

$\tt \: highest \: power \: is3 \: so \: degree \: is \\ \tt also3$

$\tt \therefore it \: is \: not \: an \: quadratic \: eq.$

$\tt(c)3 + x + {x}^{2} = 0$

$\tt \: highest \: power \: is2 \: so \: degree \: is \\ \tt also2$

$\tt \therefore it \: is \: a \: quadratic \: eq.$

$\tt(d) {x}^{2} - 9= 0$

$\tt \: highest \: power \: is2 \: so \: degree \: is \\ \tt also2$

$\tt \therefore it \: is \: a \: quadratic \: eq.$

$\boxed{ \tt hence,(b) \: is \: not \: a \: quadratic \: eq.}$