3x^2-2(x^2+4)=42

Solution for 3x^2-2(x^2+4)=42 equation:

Simplifying
3x2 + -2(x2 + 4) = 42

Reorder the terms:
3x2 + -2(4 + x2) = 42
3x2 + (4 * -2 + x2 * -2) = 42
3x2 + (-8 + -2x2) = 42

Reorder the terms:
-8 + 3x2 + -2x2 = 42

Combine like terms: 3x2 + -2x2 = 1x2
-8 + 1x2 = 42

Solving
-8 + 1x2 = 42

Solving for variable 'x'.

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

Add '8' to each side of the equation.
-8 + 8 + 1x2 = 42 + 8

Combine like terms: -8 + 8 = 0
0 + 1x2 = 42 + 8
1x2 = 42 + 8

Combine like terms: 42 + 8 = 50
1x2 = 50

Divide each side by '1'.
x2 = 50

Simplifying
x2 = 50

Take the square root of each side:
x = {-7.071067812, 7.071067812}