Function negative for all values of x

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SUMMARY

The function 3x² - 12x + m cannot be negative for all values of x, as established in the discussion. The critical condition derived from the discriminant, b² - 4ac < 0, leads to the conclusion that m must be greater than 12. However, substituting m = 13 and x = 1 yields a positive result, confirming that no value of m can satisfy the requirement for the function to remain negative across all x. The graph of the function opens upwards, indicating that it can take on positive values regardless of m.

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Homework Statement


Find the range of values of m for which the function 3x^2 -12x + m is negative for all values of x.

Homework Equations


Is it possible for the function to be negative ? If so, how ?

The Attempt at a Solution


I tried using b^2 - 4ac < 0 and the result is m > 12 . However when i tried substituting *13* as the value of m and *1* as the value of x, the result is a positive number.
 
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I don't think that any such value of m exists. Just picture this intuitively. What does the graph look like? Is it shaped like a smiley expression or sad expression? Moreover, even if the discriminant is less than zero it just means that the graph doesn't cut the x-axis. It doesn't mean that it is below the x-axis.
 
Defennder is correct: No such value of m exists. Complete the square, or just see that 3x^2 - 12x itself can be made as large as required to cancel out any value of m.
 

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