Select all of the following that are quadratic equations. 1. x2 + 3 x -5 = 0
2. x2 - x = 3 x + 7
3. 5 x - 7 = 0
4. 7 x2 + 14 x = 0
5. x3 - 3 x2 + 1 = 0
6. x - 5 = 9 x + 7

1. x² + 3x - 5 = 0

2. x² - x = 3 x + 7

4. 7x² + 14x = 0

Step-by-step explanation:

A Quadratic equation takes the form;

ax² + bx + c = 0

a, b, c are constants and a cannot be 0.

Options 1 fits this;

x² + 3x - 5 = 0

Option 2 fits this as well;

x² - x = 3 x + 7  

x² -x - 3x - 7 = 0

x² - 4x - 7 = 0

Option 4 fits this as well if c = 0.

7x² + 14x + 0 = 0