Observe the equations:

x^{4} - 13x^{2} + 36 = 0

9x^{4} - 13x^{2} + 4 = 0

x^{4} - 5x^{2 }+ 6 = 0

Note that the first members are 4th degree polynomials in variable x, having a term in x^{4}, a term in x^{2} and a constant term. The second members are null.

We call these equations of **square equations.**

That is, the equation with a variable x is every equation of the form:

ax |

Examples:

x^{4} - 5x^{2} + 4 = 0

x^{4} - 8x^{2} = 0

3x^{4} - 27 = 0

Caution!

The equations below **they are not** because in a square equation the variable x has only even exponents.

x^{4} - 2x^{3} + x^{2} + 1 = 0

6x^{4 }+ 2x^{3} - 2x = 0

x^{4} - 3x = 0