3(x+1)(x-4)=0

Solution for 3(x+1)(x-4)=0 equation:

Simplifying
3(x + 1)(x + -4) = 0

Reorder the terms:
3(1 + x)(x + -4) = 0

Reorder the terms:
3(1 + x)(-4 + x) = 0

Multiply (1 + x) * (-4 + x)
3(1(-4 + x) + x(-4 + x)) = 0
3((-4 * 1 + x * 1) + x(-4 + x)) = 0
3((-4 + 1x) + x(-4 + x)) = 0
3(-4 + 1x + (-4 * x + x * x)) = 0
3(-4 + 1x + (-4x + x2)) = 0

Combine like terms: 1x + -4x = -3x
3(-4 + -3x + x2) = 0
(-4 * 3 + -3x * 3 + x2 * 3) = 0
(-12 + -9x + 3x2) = 0

Solving
-12 + -9x + 3x2 = 0

Solving for variable 'x'.

Factor out the Greatest Common Factor (GCF), '3'.
3(-4 + -3x + x2) = 0

Factor a trinomial.
3((-1 + -1x)(4 + -1x)) = 0

Ignore the factor 3.
Subproblem 1
Set the factor '(-1 + -1x)' equal to zero and attempt to solve:

Simplifying
-1 + -1x = 0

Solving
-1 + -1x = 0

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

Add '1' to each side of the equation.
-1 + 1 + -1x = 0 + 1

Combine like terms: -1 + 1 = 0
0 + -1x = 0 + 1
-1x = 0 + 1

Combine like terms: 0 + 1 = 1
-1x = 1

Divide each side by '-1'.
x = -1

Simplifying
x = -1
Subproblem 2
Set the factor '(4 + -1x)' equal to zero and attempt to solve:

Simplifying
4 + -1x = 0

Solving
4 + -1x = 0

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

Add '-4' to each side of the equation.
4 + -4 + -1x = 0 + -4

Combine like terms: 4 + -4 = 0
0 + -1x = 0 + -4
-1x = 0 + -4

Combine like terms: 0 + -4 = -4
-1x = -4

Divide each side by '-1'.
x = 4

Simplifying
x = 4
Solution
x = {-1, 4}