Class 10

Math

All topics

Quadratic Equations

Which of the following is a quadratic equation?

- $x_{21}+2x+3=0$
- $(x−1)(x+4)=x_{2}+1$
- $x_{4}−x+5=0$
- $(2x+1)(3x−4)=2x_{2}+3$

Considering second option, we get

$(x−1)(x+4)=x_{2}+1$

$x_{2}+3x−4=x_{2}+1$

$3x−5=0$ .... a linear equation is one variable.

$x_{4}−x+5=0$ is not a quadratic equation since the degree is $4$.

Considering the last option

$(2x+1)(3x−4)=2x_{2}+3$

$6x_{2}−5x−4=2x_{2}+3$

$4x_{2}−5x−7=0$ ..... Hence a quadratic equation.