Mister Exam
Other calculators
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How to use it?
- Equation:
-
Equation 9^x-8*3^x-9=0
- Equation x+y=4
-
Equation 5x+8=-12
-
Equation x/9+x=-3
- Express {x} in terms of y where:
- 18*x+17*y=-14
- 16*x-17*y=-15
- -4*x-4*y=19
- 15*x+1*y=19
- Graphing y =:
- x^2-2x-4
-
Identical expressions
- x^ two -2x- four = zero
- x squared minus 2x minus 4 equally 0
- x to the power of two minus 2x minus four equally zero
- x2-2x-4=0
- x²-2x-4=0
- x to the power of 2-2x-4=0
- x^2-2x-4=O
-
Similar expressions
- x^2-2x+4=0
- x^2+2x-4=0
x^2-2x-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
$$a = 1$$
$$b = -2$$
$$c = -4$$
, then
Because D > 0, then the equation has two roots.
or
$$x_{1} = 1 + \sqrt{5}$$
$$x_{2} = 1 - \sqrt{5}$$
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
$$a = 1$$
$$b = -2$$
$$c = -4$$
, then
D = b^2 - 4 * a * c =
(-2)^2 - 4 * (1) * (-4) = 20
Because D > 0, then the equation has two roots.
x1 = (-b + sqrt(D)) / (2*a)
x2 = (-b - sqrt(D)) / (2*a)
or
$$x_{1} = 1 + \sqrt{5}$$
$$x_{2} = 1 - \sqrt{5}$$
Vieta's Theorem
it is reduced quadratic equation
$$p x + q + x^{2} = 0$$
where
$$p = \frac{b}{a}$$
$$p = -2$$
$$q = \frac{c}{a}$$
$$q = -4$$
Vieta Formulas
$$x_{1} + x_{2} = - p$$
$$x_{1} x_{2} = q$$
$$x_{1} + x_{2} = 2$$
$$x_{1} x_{2} = -4$$
$$p x + q + x^{2} = 0$$
where
$$p = \frac{b}{a}$$
$$p = -2$$
$$q = \frac{c}{a}$$
$$q = -4$$
Vieta Formulas
$$x_{1} + x_{2} = - p$$
$$x_{1} x_{2} = q$$
$$x_{1} + x_{2} = 2$$
$$x_{1} x_{2} = -4$$
Sum and product of roots
[src]
sum
___ ___ 1 - \/ 5 + 1 + \/ 5
$$\left(1 - \sqrt{5}\right) + \left(1 + \sqrt{5}\right)$$
=
2
$$2$$
product
/ ___\ / ___\ \1 - \/ 5 /*\1 + \/ 5 /
$$\left(1 - \sqrt{5}\right) \left(1 + \sqrt{5}\right)$$
=
-4
$$-4$$
-4
Rapid solution
[src]
___ x1 = 1 - \/ 5
$$x_{1} = 1 - \sqrt{5}$$
___ x2 = 1 + \/ 5
$$x_{2} = 1 + \sqrt{5}$$
x2 = 1 + sqrt(5)
The graph