Mister Exam
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- x^ two -x+ thirty = zero
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Similar expressions
- x^2+x+30=0
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x^2-x+30=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
$$a = 1$$
$$b = -1$$
$$c = 30$$
, then
Because D<0, then the equation
has no real roots,
but complex roots is exists.
or
$$x_{1} = \frac{1}{2} + \frac{\sqrt{119} i}{2}$$
$$x_{2} = \frac{1}{2} - \frac{\sqrt{119} i}{2}$$
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) = -119
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
$$x_{1} = \frac{1}{2} + \frac{\sqrt{119} i}{2}$$
$$x_{2} = \frac{1}{2} - \frac{\sqrt{119} i}{2}$$
Vieta's Theorem
it is reduced quadratic equation
$$p x + q + x^{2} = 0$$
where
$$p = \frac{b}{a}$$
$$p = -1$$
$$q = \frac{c}{a}$$
$$q = 30$$
Vieta Formulas
$$x_{1} + x_{2} = - p$$
$$x_{1} x_{2} = q$$
$$x_{1} + x_{2} = 1$$
$$x_{1} x_{2} = 30$$
$$p x + q + x^{2} = 0$$
where
$$p = \frac{b}{a}$$
$$p = -1$$
$$q = \frac{c}{a}$$
$$q = 30$$
Vieta Formulas
$$x_{1} + x_{2} = - p$$
$$x_{1} x_{2} = q$$
$$x_{1} + x_{2} = 1$$
$$x_{1} x_{2} = 30$$
Rapid solution
[src]
_____
1 I*\/ 119
x1 = - - ---------
2 2
$$x_{1} = \frac{1}{2} - \frac{\sqrt{119} i}{2}$$
_____
1 I*\/ 119
x2 = - + ---------
2 2
$$x_{2} = \frac{1}{2} + \frac{\sqrt{119} i}{2}$$
x2 = 1/2 + sqrt(119)*i/2
Sum and product of roots
[src]
sum
_____ _____ 1 I*\/ 119 1 I*\/ 119 - - --------- + - + --------- 2 2 2 2
$$\left(\frac{1}{2} - \frac{\sqrt{119} i}{2}\right) + \left(\frac{1}{2} + \frac{\sqrt{119} i}{2}\right)$$
=
1
$$1$$
product
/ _____\ / _____\ |1 I*\/ 119 | |1 I*\/ 119 | |- - ---------|*|- + ---------| \2 2 / \2 2 /
$$\left(\frac{1}{2} - \frac{\sqrt{119} i}{2}\right) \left(\frac{1}{2} + \frac{\sqrt{119} i}{2}\right)$$
=
30
$$30$$
30
Numerical answer
[src]
x1 = 0.5 - 5.45435605731786*i
x2 = 0.5 + 5.45435605731786*i
x2 = 0.5 + 5.45435605731786*i