2c^2+8c^2-42=0

Solution for 2c^2+8c^2-42=0 equation:

Simplifying
2c2 + 8c2 + -42 = 0

Reorder the terms:
-42 + 2c2 + 8c2 = 0

Combine like terms: 2c2 + 8c2 = 10c2
-42 + 10c2 = 0

Solving
-42 + 10c2 = 0

Solving for variable 'c'.

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

Add '42' to each side of the equation.
-42 + 42 + 10c2 = 0 + 42

Combine like terms: -42 + 42 = 0
0 + 10c2 = 0 + 42
10c2 = 0 + 42

Combine like terms: 0 + 42 = 42
10c2 = 42

Divide each side by '10'.
c2 = 4.2

Simplifying
c2 = 4.2

Take the square root of each side:
c = {-2.049390153, 2.049390153}