SOLUTION: twelve more than one-half the square of a number is 30. What is the number?

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Question 1190755: twelve more than one-half the square of a number is 30. What is the number?
Answer by ikleyn(52803) About Me  (Show Source):
You can put this solution on YOUR website!
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            Solve backward  MENTALLY. 


    30 minus 12 is one-half of the square,

or

    18 is one-half of the square


Hence, the square is two times 18, i.e. 36.


It means that the number is the square root of 36, i.e. plus or minus 6.


ANSWER.  The number is 6 or -6.

Solved mentally.