Simplifying
5j2 + -20 = 0

Reorder the terms:
-20 + 5j2 = 0

Solving
-20 + 5j2 = 0

Solving for variable 'j'.

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

Add '20' to each side of the equation.
-20 + 20 + 5j2 = 0 + 20

Combine like terms: -20 + 20 = 0
0 + 5j2 = 0 + 20
5j2 = 0 + 20

Combine like terms: 0 + 20 = 20
5j2 = 20

Divide each side by '5'.
j2 = 4

Simplifying
j2 = 4

Reorder the terms:
-4 + j2 = 4 + -4

Combine like terms: 4 + -4 = 0
-4 + j2 = 0

Factor a difference between two squares.
(2 + j)(-2 + j) = 0

Subproblem 1
Set the factor '(2 + j)' equal to zero and attempt to solve:

Simplifying
2 + j = 0

Solving
2 + j = 0

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

Add '-2' to each side of the equation.
2 + -2 + j = 0 + -2

Combine like terms: 2 + -2 = 0
0 + j = 0 + -2
j = 0 + -2

Combine like terms: 0 + -2 = -2
j = -2

Simplifying
j = -2
Subproblem 2
Set the factor '(-2 + j)' equal to zero and attempt to solve:

Simplifying
-2 + j = 0

Solving
-2 + j = 0

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

Add '2' to each side of the equation.
-2 + 2 + j = 0 + 2

Combine like terms: -2 + 2 = 0
0 + j = 0 + 2
j = 0 + 2

Combine like terms: 0 + 2 = 2
j = 2

Simplifying
j = 2
Solution
j = {-2, 2}