42=7x(2x)

Solution for 42=7x(2x) equation:

Simplifying
42 = 7x(2x)

Remove parenthesis around (2x)
42 = 7x * 2x

Reorder the terms for easier multiplication:
42 = 7 * 2x * x

Multiply 7 * 2
42 = 14x * x

Multiply x * x
42 = 14x2

Solving
42 = 14x2

Solving for variable 'x'.

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

Add '-14x2' to each side of the equation.
42 + -14x2 = 14x2 + -14x2

Combine like terms: 14x2 + -14x2 = 0
42 + -14x2 = 0

Add '-42' to each side of the equation.
42 + -42 + -14x2 = 0 + -42

Combine like terms: 42 + -42 = 0
0 + -14x2 = 0 + -42
-14x2 = 0 + -42

Combine like terms: 0 + -42 = -42
-14x2 = -42

Divide each side by '-14'.
x2 = 3

Simplifying
x2 = 3

Take the square root of each side:
x = {-1.732050808, 1.732050808}