Y=-0.9(x+3)(x-3)

Solution for Y=-0.9(x+3)(x-3) equation:

Simplifying
Y = -0.9(x + 3)(x + -3)

Reorder the terms:
Y = -0.9(3 + x)(x + -3)

Reorder the terms:
Y = -0.9(3 + x)(-3 + x)

Multiply (3 + x) * (-3 + x)
Y = -0.9(3(-3 + x) + x(-3 + x))
Y = -0.9((-3 * 3 + x * 3) + x(-3 + x))
Y = -0.9((-9 + 3x) + x(-3 + x))
Y = -0.9(-9 + 3x + (-3 * x + x * x))
Y = -0.9(-9 + 3x + (-3x + x2))

Combine like terms: 3x + -3x = 0
Y = -0.9(-9 + 0 + x2)
Y = -0.9(-9 + x2)
Y = (-9 * -0.9 + x2 * -0.9)
Y = (8.1 + -0.9x2)

Solving
Y = 8.1 + -0.9x2

Solving for variable 'Y'.

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

Simplifying
Y = 8.1 + -0.9x2