y^4-5y^2+42=0

Solution for y^4-5y^2+42=0 equation:

Simplifying
y4 + -5y2 + 42 = 0

Reorder the terms:
42 + -5y2 + y4 = 0

Solving
42 + -5y2 + y4 = 0

Solving for variable 'y'.

Begin completing the square.

Move the constant term to the right:

Add '-42' to each side of the equation.
42 + -5y2 + -42 + y4 = 0 + -42

Reorder the terms:
42 + -42 + -5y2 + y4 = 0 + -42

Combine like terms: 42 + -42 = 0
0 + -5y2 + y4 = 0 + -42
-5y2 + y4 = 0 + -42

Combine like terms: 0 + -42 = -42
-5y2 + y4 = -42

The y term is -5y2.  Take half its coefficient (-2.5).
Square it (6.25) and add it to both sides.

Add '6.25' to each side of the equation.
-5y2 + 6.25 + y4 = -42 + 6.25

Reorder the terms:
6.25 + -5y2 + y4 = -42 + 6.25

Combine like terms: -42 + 6.25 = -35.75
6.25 + -5y2 + y4 = -35.75

Factor a perfect square on the left side:
(y2 + -2.5)(y2 + -2.5) = -35.75

Can't calculate square root of the right side.

The solution to this equation could not be determined.