Solution of Equations Help

    • Thread Starter

    I really need some help with this my teacher said I needed to complete a mini test for homework which we have one day to complete I've tried to search for ans answer but can find one can you please tell me the method to work this out and possibly the answer thanks.

    Check if -3 and 3 are solutions of the equation of

    Please I really would like some help soon thanks.

    that one is a lot simpler than you think.
    substitute each value to each side. lets say you wanted to know if 0 is a solution. put 0 on the left you get 0 cubed (0) and on the right root 40. 0 isnt root 40 so its not a solution.

    If the quesiton is worth like 1 mark or two literally write the equation but replace x with 3 (then after repeat with -3)

    for a 5 marker you compare values:
    3 cubed is 27, note that down
    root of 12x3+40 is root 76, 76 doesnt equal 27 therefore it's not a solution.

    -3 cubed is -27. root 12x-3 +40 is root 4 which is 2. 2 is not -27 so it's not a solution.
    TBH quite suprised it isnt asking you to actually find the solution, thats a lot more fun (and easy to do if you're not currently doing A level, then you do wierd stuff)
Write a reply… Reply
Submit reply


Thanks for posting! You just need to create an account in order to submit the post
  1. this can't be left blank
    that username has been taken, please choose another Forgotten your password?
  2. this can't be left blank
    this email is already registered. Forgotten your password?
  3. this can't be left blank

    6 characters or longer with both numbers and letters is safer

  4. this can't be left empty
    your full birthday is required
  1. Oops, you need to agree to our Ts&Cs to register
  2. Slide to join now Processing…

Updated: September 29, 2016
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.

Would you prefer to be told about sex by your:
Useful resources

Make your revision easier


Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here


How to use LaTex

Writing equations the easy way

Student revising

Study habits of A* students

Top tips from students who have already aced their exams

Study Planner

Create your own Study Planner

Never miss a deadline again

Polling station sign

Thinking about a maths degree?

Chat with other maths applicants

Can you help? Study help unanswered threads

Groups associated with this forum:

View associated groups
Study resources

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Quick reply
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.