We'll re-write the equation, keeping the first 3 terms to the
left side. For this teason, we'll move 2 to the right
side:
x^3+3x^2+4x = -2
We'll factorize
by x to the left side:
x(x^2 + 3x + 4) =
-2
If the solution of the equation is an integer number,x, it has to
divide -2, as well.
We'll identify the divisors of
-2:
D = -2 ; -1 ; 1 ; 2
We'll
substitute the divisor into equation.
For x =
-1
-1*[(-1)^2 + 3(-1) + 4] =
-2
-1*(4-2) = -2
-2 =
-2
x = -1 is the solution of the
equation.
We'll put x = -2:
-2*[(-2)^2
+ 3(-2) + 4] = -2
-2(4 - 6 + 4) =
-2
-2*2 = -2
-4 = -2
impossible!
x = -2 is not a solution for the
equation!
We'll put x = 1
1*[(1)^2 +
3*(1) + 4] = -2
8 = -2 impossible
x =
2
2*[(2)^2 + 3*(2) + 4] = -2
28 = -2
impossible
We notice that for positive values of x, the expression
has values bigger than -2.
The only integer solution
for the equation is x = -1.
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