You are Here: Home >< Maths

# Algebra help watch

1. How do I solve 2x-54x^-2=0?
I started with 2x(1-27x-3)=0
And got 0 and 3.
But the answer only says three, where did I go wrong?
2. if you test the numbers in the original LHS you will see that the zero cannot work.
3. This question doesn’t even make sense
4. I belive OP's equation is

which he simplified to
5. (Original post by Janej77)
How do I solve 2x-54x^-2=0?
I started with 2x(1-27x-3)=0
And got 0 and 3.
But the answer only says three, where did I go wrong?
Could you rewrite the question? It looks like you've written
6. (Original post by ManLike007)
Could you rewrite the question? It looks like you've written
2x-54x^(-2)=0
I factorised to 2x(1-27x^-3)=0
7. 2x-54x^-2=0
2x-54/x^2=0
multiply both sides by x^2
2x^3-54=0
2x^3=54
Divide both sides by 2
x^3=27
so x=3
8. (Original post by Janej77)
2x-54x^(-2)=0
I factorised to 2x(1-27x^-3)=0
Your solutions are correct to obtain the values 0 and .

However, the answer cannot be 0 and here's why (I think):

Substituting in

doesn't work because is undefined which affects the rest of the equation. Divide any number by zero you'll get an error on your calculator
9. (Original post by Novelister)
2x-54x^-2=0
2x-54/x^2=0
multiply both sides by x^2
2x^3-54=0
2x^3=54
Divide both sides by 2
x^3=27
so x=3
Dividing both sides by (for example) let alone causes you to lose solutions so always factorise when finding solutions for or whatever variable it may be.
10. (Original post by ManLike007)
Your solutions are correct to obtain the values 0 and .

However, the answer cannot be 0 and here's why (I think):

Substituting in

doesn't work because is undefined which affects the rest of the equation. Divide any number by zero you'll get an error on your calculator
Thank you

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: November 11, 2017
Today on TSR

### University open days

Wed, 25 Jul '18
2. University of Buckingham
Wed, 25 Jul '18
3. Bournemouth University
Wed, 1 Aug '18
Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams