Question

Select all of the following that are quadratic equations.

7x2 + 14x = 0
x3 - 3x2 + 1 = 0
5x - 7 = 0
x2 + 3x -5 = 0
x - 5 = 9x + 7
x2 - x = 3x + 7

Answer 1

a quadratic equation has to have x^2....it does not necessarily have to have a constant.

7x^2 + 14x = 0
x^2 + 3x - 5 = 0
x^2 - x = 3x + 7
these are quadratic

Answer 2

The quadratic equations are
`7x^2 + 14x = 0`,
`x^2 + 3x -5 = 0` and
`x^2 - x = 3x + 7`.

Explanation:

Consider the provided information.

We need to find all the quadratic equations.

The given equations are:

`7x^2 + 14x = 0`

`x^3 - 3x^2 + 1 = 0`

`5x - 7 = 0`

`x^2 + 3x -5 = 0`

`x - 5 = 9x + 7`

`x^2 - x = 3x + 7`

Quadratic equations is an equation of the second degree (degree is the highest power of x).

Now consider the provided options:

The equations having second degree are:

`7x^2 + 14x = 0` The highest power of x is 2.

`x^2 + 3x -5 = 0` The highest power of x is 2.

`x^2 - x = 3x + 7` The highest power of x is 2.

Hence, the quadratic equations are
`7x^2 + 14x = 0`,
`x^2 + 3x -5 = 0` and
`x^2 - x = 3x + 7`.