a^4-28a^2+75=0

Solution for a^4-28a^2+75=0 equation:

Simplifying
a4 + -28a2 + 75 = 0

Reorder the terms:
75 + -28a2 + a4 = 0

Solving
75 + -28a2 + a4 = 0

Solving for variable 'a'.

Factor a trinomial.
(3 + -1a2)(25 + -1a2) = 0

Factor a difference between two squares.
(3 + -1a2)((5 + a)(5 + -1a)) = 0

Subproblem 1
Set the factor '(3 + -1a2)' equal to zero and attempt to solve:

Simplifying
3 + -1a2 = 0

Solving
3 + -1a2 = 0

Move all terms containing a to the left, all other terms to the right.

Add '-3' to each side of the equation.
3 + -3 + -1a2 = 0 + -3

Combine like terms: 3 + -3 = 0
0 + -1a2 = 0 + -3
-1a2 = 0 + -3

Combine like terms: 0 + -3 = -3
-1a2 = -3

Divide each side by '-1'.
a2 = 3

Simplifying
a2 = 3

Take the square root of each side:
a = {-1.732050808, 1.732050808}
Subproblem 2
Set the factor '(5 + a)' equal to zero and attempt to solve:

Simplifying
5 + a = 0

Solving
5 + a = 0

Move all terms containing a to the left, all other terms to the right.

Add '-5' to each side of the equation.
5 + -5 + a = 0 + -5

Combine like terms: 5 + -5 = 0
0 + a = 0 + -5
a = 0 + -5

Combine like terms: 0 + -5 = -5
a = -5

Simplifying
a = -5
Subproblem 3
Set the factor '(5 + -1a)' equal to zero and attempt to solve:

Simplifying
5 + -1a = 0

Solving
5 + -1a = 0

Move all terms containing a to the left, all other terms to the right.

Add '-5' to each side of the equation.
5 + -5 + -1a = 0 + -5

Combine like terms: 5 + -5 = 0
0 + -1a = 0 + -5
-1a = 0 + -5

Combine like terms: 0 + -5 = -5
-1a = -5

Divide each side by '-1'.
a = 5

Simplifying
a = 5
Solution
a = {-1.732050808, 1.732050808, -5, 5}