42=3(x^2+5)

Solution for 42=3(x^2+5) equation:

Simplifying
42 = 3(x2 + 5)

Reorder the terms:
42 = 3(5 + x2)
42 = (5 * 3 + x2 * 3)
42 = (15 + 3x2)

Solving
42 = 15 + 3x2

Solving for variable 'x'.

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

Add '-3x2' to each side of the equation.
42 + -3x2 = 15 + 3x2 + -3x2

Combine like terms: 3x2 + -3x2 = 0
42 + -3x2 = 15 + 0
42 + -3x2 = 15

Add '-42' to each side of the equation.
42 + -42 + -3x2 = 15 + -42

Combine like terms: 42 + -42 = 0
0 + -3x2 = 15 + -42
-3x2 = 15 + -42

Combine like terms: 15 + -42 = -27
-3x2 = -27

Divide each side by '-3'.
x2 = 9

Simplifying
x2 = 9

Take the square root of each side:
x = {-3, 3}