Mister Exam
Other calculators
-
How to use it?
- Equation:
-
Equation 81*x^3+18*x^2+x=0
-
Equation 6=8-5(7x-1)
-
Equation (-x-4)*(3*x+3)=0
- Equation x^2-144=0
- Express {x} in terms of y where:
- -14*x-8*y=20
- -1*x+4*y=-10
- 8*x+6*y=20
- -11*x-19*y=14
- Graphing y =:
- x^2+5x-4
- Derivative of:
- x^2+5x-4
-
Identical expressions
- x^ two +5x- four = zero
- x squared plus 5x minus 4 equally 0
- x to the power of two plus 5x minus four equally zero
- x2+5x-4=0
- x²+5x-4=0
- x to the power of 2+5x-4=0
- x^2+5x-4=O
-
Similar expressions
- x^2-5x-4=0
- x^2+5x+4=0
x^2+5x-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
$$a = 1$$
$$b = 5$$
$$c = -4$$
, then
Because D > 0, then the equation has two roots.
or
$$x_{1} = - \frac{5}{2} + \frac{\sqrt{41}}{2}$$
$$x_{2} = - \frac{\sqrt{41}}{2} - \frac{5}{2}$$
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
$$a = 1$$
$$b = 5$$
$$c = -4$$
, then
D = b^2 - 4 * a * c =
(5)^2 - 4 * (1) * (-4) = 41
Because D > 0, then the equation has two roots.
x1 = (-b + sqrt(D)) / (2*a)
x2 = (-b - sqrt(D)) / (2*a)
or
$$x_{1} = - \frac{5}{2} + \frac{\sqrt{41}}{2}$$
$$x_{2} = - \frac{\sqrt{41}}{2} - \frac{5}{2}$$
Vieta's Theorem
it is reduced quadratic equation
$$p x + q + x^{2} = 0$$
where
$$p = \frac{b}{a}$$
$$p = 5$$
$$q = \frac{c}{a}$$
$$q = -4$$
Vieta Formulas
$$x_{1} + x_{2} = - p$$
$$x_{1} x_{2} = q$$
$$x_{1} + x_{2} = -5$$
$$x_{1} x_{2} = -4$$
$$p x + q + x^{2} = 0$$
where
$$p = \frac{b}{a}$$
$$p = 5$$
$$q = \frac{c}{a}$$
$$q = -4$$
Vieta Formulas
$$x_{1} + x_{2} = - p$$
$$x_{1} x_{2} = q$$
$$x_{1} + x_{2} = -5$$
$$x_{1} x_{2} = -4$$
Sum and product of roots
[src]
sum
____ ____ 5 \/ 41 5 \/ 41 - - + ------ + - - - ------ 2 2 2 2
$$\left(- \frac{\sqrt{41}}{2} - \frac{5}{2}\right) + \left(- \frac{5}{2} + \frac{\sqrt{41}}{2}\right)$$
=
-5
$$-5$$
product
/ ____\ / ____\ | 5 \/ 41 | | 5 \/ 41 | |- - + ------|*|- - - ------| \ 2 2 / \ 2 2 /
$$\left(- \frac{5}{2} + \frac{\sqrt{41}}{2}\right) \left(- \frac{\sqrt{41}}{2} - \frac{5}{2}\right)$$
=
-4
$$-4$$
-4
Rapid solution
[src]
____
5 \/ 41
x1 = - - + ------
2 2
$$x_{1} = - \frac{5}{2} + \frac{\sqrt{41}}{2}$$
____
5 \/ 41
x2 = - - - ------
2 2
$$x_{2} = - \frac{\sqrt{41}}{2} - \frac{5}{2}$$
x2 = -sqrt(41)/2 - 5/2