Solve y=-3x²-9: Finding Values Where Function is Positive

Look at the function below:

y=3x29 y=-3x^2-9

Determine for which values of x x the following is true:

f(x)>0 f(x) > 0

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Step-by-step written solution

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1

Understand the problem

Look at the function below:

y=3x29 y=-3x^2-9

Determine for which values of x x the following is true:

f(x)>0 f(x) > 0

2

Step-by-step solution

To solve this problem, let's analyze the function f(x)=3x29 f(x) = -3x^2 - 9 and determine when it is greater than zero.

The function is a quadratic equation of the form ax2+bx+c ax^2 + bx + c where a=3 a = -3 , b=0 b = 0 , and c=9 c = -9 .

Our task is to find when 3x29>0 -3x^2 - 9 > 0 .

Step 1: Rewrite the inequality:
3x29>0 -3x^2 - 9 > 0

Step 2: Add 9 to both sides to isolate the quadratic term:
3x2>9 -3x^2 > 9

Step 3: Divide through by -3 (note that dividing by a negative flips the inequality sign):
x2<3 x^2 < -3

Step 4: Analyze x2<3 x^2 < -3

A square of a real number x2 x^2 is always non-negative, meaning x20 x^2 \geq 0 . Therefore, x2<3 x^2 < -3 is impossible since there are no real values of x x such that the square of x x is a negative number.

Conclusion: The inequality f(x)>0 f(x) > 0 has no real solutions. Therefore, no values of x x satisfy the inequality.

The correct answer is that no values of x x will make f(x)>0 f(x) > 0 .

3

Final Answer

No values of x x

Practice Quiz

Test your knowledge with interactive questions

The graph of the function below does not intersect the \( x \)-axis.

The parabola's vertex is marked A.

Find all values of \( x \) where
\( f\left(x\right) > 0 \).

AAAX

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