Mister Exam
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How to use it?
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Equation 2*cos(x)+1=0
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Equation (-5*x-3)*(2*x-1)=0
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Identical expressions
- x^ two +5x+ nine = zero
- x squared plus 5x plus 9 equally 0
- x to the power of two plus 5x plus nine equally zero
- x2+5x+9=0
- x²+5x+9=0
- x to the power of 2+5x+9=0
- x^2+5x+9=O
-
Similar expressions
- x^2+5x-9=0
- x^2-5x+9=0
x^2+5x+9=0 equation
The teacher will be very surprised to see your correct solution 😉
The solution
Detail solution
This equation is of the form
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
$$a = 1$$
$$b = 5$$
$$c = 9$$
, then
Because D<0, then the equation
has no real roots,
but complex roots is exists.
or
$$x_{1} = - \frac{5}{2} + \frac{\sqrt{11} i}{2}$$
Simplify
$$x_{2} = - \frac{5}{2} - \frac{\sqrt{11} i}{2}$$
Simplify
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
$$a = 1$$
$$b = 5$$
$$c = 9$$
, then
D = b^2 - 4 * a * c =
(5)^2 - 4 * (1) * (9) = -11
Because D<0, then the equation
has no real roots,
but complex roots is exists.
x1 = (-b + sqrt(D)) / (2*a)
x2 = (-b - sqrt(D)) / (2*a)
or
$$x_{1} = - \frac{5}{2} + \frac{\sqrt{11} i}{2}$$
Simplify
$$x_{2} = - \frac{5}{2} - \frac{\sqrt{11} i}{2}$$
Simplify
Vieta's Theorem
it is reduced quadratic equation
$$p x + x^{2} + q = 0$$
where
$$p = \frac{b}{a}$$
$$p = 5$$
$$q = \frac{c}{a}$$
$$q = 9$$
Vieta Formulas
$$x_{1} + x_{2} = - p$$
$$x_{1} x_{2} = q$$
$$x_{1} + x_{2} = -5$$
$$x_{1} x_{2} = 9$$
$$p x + x^{2} + q = 0$$
where
$$p = \frac{b}{a}$$
$$p = 5$$
$$q = \frac{c}{a}$$
$$q = 9$$
Vieta Formulas
$$x_{1} + x_{2} = - p$$
$$x_{1} x_{2} = q$$
$$x_{1} + x_{2} = -5$$
$$x_{1} x_{2} = 9$$
Sum and product of roots
[src]
sum
____ ____
5 I*\/ 11 5 I*\/ 11
0 + - - - -------- + - - + --------
2 2 2 2
$$\left(0 - \left(\frac{5}{2} + \frac{\sqrt{11} i}{2}\right)\right) - \left(\frac{5}{2} - \frac{\sqrt{11} i}{2}\right)$$
=
-5
$$-5$$
product
/ ____\ / ____\ | 5 I*\/ 11 | | 5 I*\/ 11 | 1*|- - - --------|*|- - + --------| \ 2 2 / \ 2 2 /
$$1 \left(- \frac{5}{2} - \frac{\sqrt{11} i}{2}\right) \left(- \frac{5}{2} + \frac{\sqrt{11} i}{2}\right)$$
=
9
$$9$$
9
Rapid solution
[src]
____
5 I*\/ 11
x1 = - - - --------
2 2
$$x_{1} = - \frac{5}{2} - \frac{\sqrt{11} i}{2}$$
____
5 I*\/ 11
x2 = - - + --------
2 2
$$x_{2} = - \frac{5}{2} + \frac{\sqrt{11} i}{2}$$
Numerical answer
[src]
x1 = -2.5 - 1.6583123951777*i
x2 = -2.5 + 1.6583123951777*i
x2 = -2.5 + 1.6583123951777*i
The graph