x^2+2x^2=18

To solve the equation x^2 + 2x^2 = 18, we can start by combining like terms on the left side of the equation:

3x^2 = 18

Next, we divide both sides of the equation by 3 to isolate x^2:

x^2 = 18/3

Simplifying the right side:

x^2 = 6

To solve for x, we can take the square root of both sides of the equation:

√(x^2) = √6

This gives us two possible solutions:

x = √6 or x = -√6

So the solutions to the equation x^2 + 2x^2 = 18 are x = √6 and x = -√6.