(2x^2-6)+(5x^2+2)+(-x^2-7)=0

Solution for (2x^2-6)+(5x^2+2)+(-x^2-7)=0 equation:

Simplifying
(2x2 + -6) + (5x2 + 2) + (-1x2 + -7) = 0

Reorder the terms:
(-6 + 2x2) + (5x2 + 2) + (-1x2 + -7) = 0

Remove parenthesis around (-6 + 2x2)
-6 + 2x2 + (5x2 + 2) + (-1x2 + -7) = 0

Reorder the terms:
-6 + 2x2 + (2 + 5x2) + (-1x2 + -7) = 0

Remove parenthesis around (2 + 5x2)
-6 + 2x2 + 2 + 5x2 + (-1x2 + -7) = 0

Reorder the terms:
-6 + 2x2 + 2 + 5x2 + (-7 + -1x2) = 0

Remove parenthesis around (-7 + -1x2)
-6 + 2x2 + 2 + 5x2 + -7 + -1x2 = 0

Reorder the terms:
-6 + 2 + -7 + 2x2 + 5x2 + -1x2 = 0

Combine like terms: -6 + 2 = -4
-4 + -7 + 2x2 + 5x2 + -1x2 = 0

Combine like terms: -4 + -7 = -11
-11 + 2x2 + 5x2 + -1x2 = 0

Combine like terms: 2x2 + 5x2 = 7x2
-11 + 7x2 + -1x2 = 0

Combine like terms: 7x2 + -1x2 = 6x2
-11 + 6x2 = 0

Solving
-11 + 6x2 = 0

Solving for variable 'x'.

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

Add '11' to each side of the equation.
-11 + 11 + 6x2 = 0 + 11

Combine like terms: -11 + 11 = 0
0 + 6x2 = 0 + 11
6x2 = 0 + 11

Combine like terms: 0 + 11 = 11
6x2 = 11

Divide each side by '6'.
x2 = 1.833333333

Simplifying
x2 = 1.833333333

Take the square root of each side:
x = {-1.354006401, 1.354006401}