Question

which of the following is quadratic equation?​

Answer 1

Answer:

$\frac{1}{x} + x=2 ~~is~a~quadratic~eqation$

Step-by-step explanation:

multiplying with x on both sides

$1+x^2=2\\x^2+1-2=0\\x^2-1=0$

Answer 2

EXPLANATION.

Which of the following is quadratic equation.

Quadratic expression.

A polynomial of degree two of the form ax² + bx + c (a ≠ 0) is called a quadratic expression in x.

(A) 1/x + x = 2.

As we know that,

We can write equation as,

⇒ [(1 + x²)/x] = 2.

⇒ 1 + x² = 2x.

⇒ x² - 2x + 1 = 0.

It is in the form of quadratic expression.

(B) x⁻² + 3x + 2 = 0.

As we know that,

We can write equation as,

⇒ 1/x² + 3x + 2 = 0.

⇒ (1 + 3x³ + 2x²)/(x²) = 0.

⇒ 1 + 3x³ + 2x² = 0.

⇒ 3x³ + 2x² + 1 = 0.

It is in the form of cubic expression.

(C) z² + 7 = z² + 8.

As we know that,

We can write equation as,

⇒ z² + 7 - z² - 8 = 0.

⇒ - 1.

It is not in the form of quadratic expression.

(D) m² + 1/m² = 5.

As we know that,

We can write equation as,

⇒ (m⁴ + 1)/(m²) = 5.

⇒ m⁴ + 1 = 5m².

⇒ m⁴ - 5m² + 1 = 0.

It is in the form of biquadratic expression.

Hence, option [A] is correct answer.