SOLUTION: Hello, can someone help me factor this problem? 1.m^3-27 I need help trying to solve these problems 1.x^3-x^2-20x=0 2.5x^2+3x=2 3.x(x-x5)=36 Thanks

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Hello, can someone help me factor this problem? 1.m^3-27 I need help trying to solve these problems 1.x^3-x^2-20x=0 2.5x^2+3x=2 3.x(x-x5)=36 Thanks      Log On


   

Question 44278: Hello, can someone help me factor this problem?
1.m^3-27
I need help trying to solve these problems
1.x^3-x^2-20x=0
2.5x^2+3x=2
3.x(x-x5)=36
Thanks
Answer by adamchapman(301) About Me  (Show Source):
You can put this solution on YOUR website!
m%5E3-27+=%28m-3%29%5E3
m%5E3-27+=%28m-3%29%28m-3%29%28m-3%29
For the remaining problems, you need to simplify and rearrange the expressions to give a quadratic equation of the form ax%5E2%2Bbx%2Bc=0which can be solved using the solver x+=+%28-b+%2B-+sqrt%28+b%5E2-4ac+%29%29%2F%282a%29+.
For the first of these problems submitted you should divide both sides by x to give: x%5E2-x-20=0
Now use x+=+%28-b+%2B-+sqrt%28+b%5E2-4ac+%29%29%2F%282a%29+
where
a=1
b=-1
c=20
To get x+=+%281+%2B-+sqrt%28+1-80+%29%29%2F2+
x+=+%281+%2B-+sqrt%28+-79+%29%29%2F2+
x+=+%281+%2B-+%28sqrt%28+79+%29%29i%29%2F2+
where "i" denotes the imaginary number i=sqrt%28-1%29.
The second and third of these problems require simplifying and rearranging to give quadratic equations of the form ax%5E2%2Bbx%2Bc=0 which can be fairly easily solved.
The second one should be rearranged to give 5x%5E2%2B3x-2=0, then use the quadratic solver already mentioned to obtain x=%28-3+%2B-+7%29%2F10.


I hope this helps.
P.S. I am trying to start up my own homework help website. I would be extremely grateful if you would e-mail me some feedback on the help you received to adam.chapman@student.manchester.ac.uk