# Pure Maths Proove that QuestionWatch

#1
Prove that, for all values of x,
x^2 +6x+18>2-1/2x
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9 months ago
#2
move all the terms to the left. then find the minimum point of the function on the LHS. if the y value is positive you have proved what was needed.
alternatively you can work with the discriminant of the LHS... if it is negative you have proved what is needed.
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9 months ago
#3
What are those blocks?

Is the problem:

x^2 + 6x + 18 > 2-0.5x?

--> x^2 + 6.5x + 16 > 0. This has no solutions as b^2-4ac>0 or you can evaluate the minimum point to be positive, etc.
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#4
(Original post by the bear)
move all the terms to the left. then find the minimum point of the function on the LHS. if the y value is positive you have proved what was needed.
alternatively you can work with the discriminant of the LHS... if it is negative you have proved what is needed.

Using b^2-4ac I found that it =-21.75
Is this right? Is that all I have to do?
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