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(x-3)*(x+4)-18=0

(x-3)*(x+4)-18=0 equation

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Numerical solution:

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The solution

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(x - 3)*(x + 4) - 18 = 0
$$\left(x - 3\right) \left(x + 4\right) - 18 = 0$$
Detail solution
Expand the expression in the equation
$$\left(x - 3\right) \left(x + 4\right) - 18 = 0$$
We get the quadratic equation
$$x^{2} + x - 30 = 0$$
This equation is of the form
a*x^2 + b*x + c = 0

A quadratic equation can be solved
using the discriminant.
The roots of the quadratic equation:
$$x_{1} = \frac{\sqrt{D} - b}{2 a}$$
$$x_{2} = \frac{- \sqrt{D} - b}{2 a}$$
where D = b^2 - 4*a*c - it is the discriminant.
Because
$$a = 1$$
$$b = 1$$
$$c = -30$$
, then
D = b^2 - 4 * a * c = 

(1)^2 - 4 * (1) * (-30) = 121

Because D > 0, then the equation has two roots.
x1 = (-b + sqrt(D)) / (2*a)

x2 = (-b - sqrt(D)) / (2*a)

or
$$x_{1} = 5$$
$$x_{2} = -6$$
The graph
Sum and product of roots [src]
sum
-6 + 5
$$-6 + 5$$
=
-1
$$-1$$
product
-6*5
$$- 30$$
=
-30
$$-30$$
-30
Rapid solution [src]
x1 = -6
$$x_{1} = -6$$
x2 = 5
$$x_{2} = 5$$
x2 = 5
Numerical answer [src]
x1 = 5.0
x2 = -6.0
x2 = -6.0
The graph
(x-3)*(x+4)-18=0 equation