Solve the equation 5x - x² = 0?

2008-04-08 1:19 pm
x = -2.24 (to 2 decimal places)


am i right?

回答 (13)

2008-04-08 4:09 pm
✔ 最佳答案
x (5 - x) = 0
x = 0 , x = 5

OR

x² - 5x = 0
x = [ 5 ± √ (25) ] / 2
x = [ 5 ± 5 ] / 2
x = 0 , x = 5 (as above)
2008-04-10 1:48 pm
Question Number 1 :
For this equation -x^2 + 5*x = 0 , answer the following questions :
A. Calculate the Determinant ! Explain what it means !
B. Calculate the Roots ( x1 and x2 ) !
C. Use factorization to find the root of the equation !

Answer Number 1 :
The equation -x^2 + 5*x = 0 is already in a*x^2+b*x+c=0 form.
So we can imply that the value of a = -1, b = 5, c = 0.

1A. Calculate the Determinant ! Explain what it means !
The formula Determinant = b^2-4*a*c is useful to solve this problem.
Since the value of a = -1, b = 5 and c = 0 are known,
the value of a and b inside Determinant = b^2-4*a*c, can be subtituted using the values we know.
So Determinant = (5)^2 - 4 * (-1)*(0)
Which is the same as Determinant = 25+0
We get following answer : Determinant = 25
Positive Determinant value, means that f(x) = -x^2 + 5*x is going to intersect x axis in two points.

1B. Calculate the Roots ( x1 and x2 ) !
By using abc formula the value of x is both
x1 = (-b+sqrt(b^2-4*a*c))/(2*a) and x2 = (-b-sqrt(b^2-4*a*c))/(2*a)
As we know that a = -1, b = 5 and c = 0,
then the value a,b and c in the abc formula, can be subtituted.
So x1 = (-(5) + sqrt( (5)^2 - 4 * (-1)*(0)))/(2*-1) and x2 = (-(5) - sqrt( (5)^2 - 4 * (-1)*(0)))/(2*-1)
Which is the same as x1 = ( -5 + sqrt( 25+0))/(-2) and x2 = ( -5 - sqrt( 25+0))/(-2)
Which is can be turned into x1 = ( -5 + sqrt( 25))/(-2) and x2 = ( -5 - sqrt( 25))/(-2)
It imply that x1 = ( -5 + 5 )/(-2) and x2 = ( -5 - 5 )/(-2)
We get following answers x1 = 0 and x2 = 5

1C. Use factorization to find the root of the equation !
-x^2 + 5*x = 0
<=> ( x ) * ( x - 5 ) = 0
We get following answers x1 = 0 and x2 = 5
參考: Download a Quadratic Solver here : http://www.mediafire.com/?6djscos0jri
2008-04-08 2:32 pm
5x - x^2 = 0
x(5 - x) = 0

x = 0

5 - x = 0
x = 5

∴ x = 0 , 5
2008-04-08 1:34 pm
nah, x has to equal 5 or 0

5(5) - 5^2 = 0
25 - 25 = 0


5(0) - 0^2 = 0
0 - 0 = 0
2008-04-08 1:34 pm
no...
should be...
5x - x^2 = 0
factorise it...
x (5 - x) = 0
x = 0 or 5 - x = 0
- x = - 5
x = 5
the answer is x = 0 or x = 5...
it has 2 answer...
2008-04-08 1:29 pm
the answer is x=0 and x=5
2008-04-08 1:28 pm
5x - x^2 = 0
x(5 - x) = 0
x = 0 or x = 5
2008-04-08 1:44 pm
The question isn't whether you are right the question is will this particular type of mathematics's help you in any way? The answer to that is no. Accounting, Economics and Statistics are all you need. Are you really going to become a medical engineer or something like that? Why would you put your self through that?

After my rant I went and answered your question x = {0, 5}
2008-04-08 1:31 pm
The answer is 12. You have to differentiate the integral of pi and the circumference of the zero provided. Use Newton's Method and a random game of ping pong to develop your final answer.

And so, my fellow Americans, ask not what your country can do for you. Ask what you can do for your country.
2008-04-08 1:27 pm
x = 5


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