3[x^2+4]=13

Solution for 3[x^2+4]=13 equation:

Simplifying
3[x2 + 4] = 13

Reorder the terms:
3[4 + x2] = 13
[4 * 3 + x2 * 3] = 13
[12 + 3x2] = 13

Solving
12 + 3x2 = 13

Solving for variable 'x'.

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

Add '-12' to each side of the equation.
12 + -12 + 3x2 = 13 + -12

Combine like terms: 12 + -12 = 0
0 + 3x2 = 13 + -12
3x2 = 13 + -12

Combine like terms: 13 + -12 = 1
3x2 = 1

Divide each side by '3'.
x2 = 0.3333333333

Simplifying
x2 = 0.3333333333

Take the square root of each side:
x = {-0.577350269, 0.577350269}