(x+3.5)(x+-3.5)=0

Solution for (x+3.5)(x+-3.5)=0 equation:

Simplifying
(x + 3.5)(x + -3.5) = 0

Reorder the terms:
(3.5 + x)(x + -3.5) = 0

Reorder the terms:
(3.5 + x)(-3.5 + x) = 0

Multiply (3.5 + x) * (-3.5 + x)
(3.5(-3.5 + x) + x(-3.5 + x)) = 0
((-3.5 * 3.5 + x * 3.5) + x(-3.5 + x)) = 0
((-12.25 + 3.5x) + x(-3.5 + x)) = 0
(-12.25 + 3.5x + (-3.5 * x + x * x)) = 0
(-12.25 + 3.5x + (-3.5x + x2)) = 0

Combine like terms: 3.5x + -3.5x = 0.0
(-12.25 + 0.0 + x2) = 0
(-12.25 + x2) = 0

Solving
-12.25 + x2 = 0

Solving for variable 'x'.

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

Add '12.25' to each side of the equation.
-12.25 + 12.25 + x2 = 0 + 12.25

Combine like terms: -12.25 + 12.25 = 0.00
0.00 + x2 = 0 + 12.25
x2 = 0 + 12.25

Combine like terms: 0 + 12.25 = 12.25
x2 = 12.25

Simplifying
x2 = 12.25

Take the square root of each side:
x = {-3.5, 3.5}