Mister Exam
Other calculators
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How to use it?
- Equation:
-
Equation x^2-8*x+15=0
-
Equation -x^2+4x+3=x^2-x-(1+2x^2)
-
Equation 3x+3=5x
-
Equation x^2+3x-4=0
- Express {x} in terms of y where:
- -17*x+2*y=9
- -13*x+7*y=-15
- -14*x-8*y=20
- -1*x+4*y=-10
-
Identical expressions
- x^ two +3x+ four = zero
- x squared plus 3x plus 4 equally 0
- x to the power of two plus 3x plus four equally zero
- x2+3x+4=0
- x²+3x+4=0
- x to the power of 2+3x+4=0
- x^2+3x+4=O
-
Similar expressions
- x^2-3x+4=0
- x^2+3x-4=0
x^2+3x+4=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
$$a = 1$$
$$b = 3$$
$$c = 4$$
, then
Because D<0, then the equation
has no real roots,
but complex roots is exists.
or
$$x_{1} = - \frac{3}{2} + \frac{\sqrt{7} i}{2}$$
$$x_{2} = - \frac{3}{2} - \frac{\sqrt{7} i}{2}$$
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
$$a = 1$$
$$b = 3$$
$$c = 4$$
, then
D = b^2 - 4 * a * c =
(3)^2 - 4 * (1) * (4) = -7
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
$$x_{1} = - \frac{3}{2} + \frac{\sqrt{7} i}{2}$$
$$x_{2} = - \frac{3}{2} - \frac{\sqrt{7} i}{2}$$
Vieta's Theorem
it is reduced quadratic equation
$$p x + q + x^{2} = 0$$
where
$$p = \frac{b}{a}$$
$$p = 3$$
$$q = \frac{c}{a}$$
$$q = 4$$
Vieta Formulas
$$x_{1} + x_{2} = - p$$
$$x_{1} x_{2} = q$$
$$x_{1} + x_{2} = -3$$
$$x_{1} x_{2} = 4$$
$$p x + q + x^{2} = 0$$
where
$$p = \frac{b}{a}$$
$$p = 3$$
$$q = \frac{c}{a}$$
$$q = 4$$
Vieta Formulas
$$x_{1} + x_{2} = - p$$
$$x_{1} x_{2} = q$$
$$x_{1} + x_{2} = -3$$
$$x_{1} x_{2} = 4$$
Sum and product of roots
[src]
sum
___ ___ 3 I*\/ 7 3 I*\/ 7 - - - ------- + - - + ------- 2 2 2 2
$$\left(- \frac{3}{2} - \frac{\sqrt{7} i}{2}\right) + \left(- \frac{3}{2} + \frac{\sqrt{7} i}{2}\right)$$
=
-3
$$-3$$
product
/ ___\ / ___\ | 3 I*\/ 7 | | 3 I*\/ 7 | |- - - -------|*|- - + -------| \ 2 2 / \ 2 2 /
$$\left(- \frac{3}{2} - \frac{\sqrt{7} i}{2}\right) \left(- \frac{3}{2} + \frac{\sqrt{7} i}{2}\right)$$
=
4
$$4$$
4
Rapid solution
[src]
___
3 I*\/ 7
x1 = - - - -------
2 2
$$x_{1} = - \frac{3}{2} - \frac{\sqrt{7} i}{2}$$
___
3 I*\/ 7
x2 = - - + -------
2 2
$$x_{2} = - \frac{3}{2} + \frac{\sqrt{7} i}{2}$$
x2 = -3/2 + sqrt(7)*i/2
Numerical answer
[src]
x1 = -1.5 - 1.3228756555323*i
x2 = -1.5 + 1.3228756555323*i
x2 = -1.5 + 1.3228756555323*i
The graph