The equation

X*X*X-X=45

has a solution between 3 and 4

use a trial and improvement method to find this solution

give your solution correct to 1 decimal place

you must show all you working

X*X*X-X=45

has a solution between 3 and 4

use a trial and improvement method to find this solution

give your solution correct to 1 decimal place

you must show all you working

Guest Mar 1, 2012

#1**0 **

step 1:

X=3

X*X*X-X = X^3-3 = 3^3-3 =**24**

step2:

X=4

X*X*X-X = X^3-4 = 4^3-4 =**60**

step3: (left=3, right=4)

middle = (left+right)/2 = (3+4)/2 = 7/2 = 3.5

X*X*X-X = 3.5^3-3.5 =**39.375**

here you see, that the right side of the equation**45** is between 39.375 and 60. so the X is between middle and right (3.5 and 4) and not between (3 and 3.5).

step4: (left=3.5, right=4)

middle = (left+right)/2 = (3.5+4)/2 = 3.75

X*X*X-X = 3.75^3-3.75 =**48.984375**

so X is between*left* and *middle*.

step5: (left=3.5, right=3.75)

and so on...

[input]X*X*X-X=45[/input]

tom:The equation

X*X*X-X=45

has a solution between 3 and 4

use a trial and improvement method to find this solution

give your solution correct to 1 decimal place

you must show all you working

step 1:

X=3

X*X*X-X = X^3-3 = 3^3-3 =

step2:

X=4

X*X*X-X = X^3-4 = 4^3-4 =

step3: (left=3, right=4)

middle = (left+right)/2 = (3+4)/2 = 7/2 = 3.5

X*X*X-X = 3.5^3-3.5 =

here you see, that the right side of the equation

step4: (left=3.5, right=4)

middle = (left+right)/2 = (3.5+4)/2 = 3.75

X*X*X-X = 3.75^3-3.75 =

so X is between

step5: (left=3.5, right=3.75)

and so on...

[input]X*X*X-X=45[/input]

admin
Mar 1, 2012