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Solution of Equations Help

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1. 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.

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

Please I really would like some help soon thanks.
2. 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)

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Updated: September 29, 2016
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