Solving for Positive Values: When is y = -3/5x^2 Greater Than Zero?

Quadratic Functions with Negative Leading Coefficients

Given the function:

y=35x2 y=-\frac{3}{5}x^2

Determine for which values of x the following holds:

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

❤️ Continue Your Math Journey!

We have hundreds of course questions with personalized recommendations + Account 100% premium

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Given the function:

y=35x2 y=-\frac{3}{5}x^2

Determine for which values of x the following holds:

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

2

Step-by-step solution

The function y=35x2 y = -\frac{3}{5}x^2 is quadratic with a negative leading coefficient, meaning the parabola opens downward. This implies that the function cannot be greater than zero for any real value of x x because it reaches its maximum (zero) at x=0 x = 0 and decreases as x |x| increases.

Therefore, there are no x x values for which f(x)>0 f(x) > 0 .

The correct choice reflecting this conclusion is: No x.

3

Final Answer

x0 x\ne0

Key Points to Remember

Essential concepts to master this topic
  • Shape Rule: Negative leading coefficient means parabola opens downward
  • Maximum Point: At vertex x = 0, y = 0 is the highest value
  • Check Values: Test x = 1: y = -3/5(1)² = -3/5 < 0 ✓

Common Mistakes

Avoid these frequent errors
  • Confusing the question with finding where the function equals zero
    Don't solve -3/5x² = 0 thinking that gives positive values = you'll find x = 0 but miss that the function is never positive! This confuses where the function crosses zero with where it's above zero. Always check if the parabola opens up or down first.

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

FAQ

Everything you need to know about this question

Why can't this function ever be positive?

+

Since the leading coefficient is negative (-3/5), the parabola opens downward like an upside-down U. The highest point is at the vertex where y=0 y = 0 , so it can never go above zero.

What's the difference between f(x) > 0 and f(x) = 0?

+

f(x) = 0 asks where the function equals zero (touches the x-axis). f(x) > 0 asks where the function is above the x-axis. For this downward parabola, it equals zero at x = 0 but is never above zero.

How do I know which way a parabola opens?

+

Look at the coefficient of x2 x^2 ! If it's positive, the parabola opens upward (U-shape). If it's negative, it opens downward (upside-down U).

Could I graph this to double-check my answer?

+

Absolutely! Graphing y=35x2 y = -\frac{3}{5}x^2 shows a downward parabola that touches the x-axis at (0,0) but never goes above it. This confirms there are no values where f(x) > 0.

What if the question asked for f(x) ≥ 0 instead?

+

Then the answer would be x = 0 only! The symbol ≥ means "greater than or equal to" so it includes the point where the function equals zero.

🌟 Unlock Your Math Potential

Get unlimited access to all 18 The Quadratic Function questions, detailed video solutions, and personalized progress tracking.

📹

Unlimited Video Solutions

Step-by-step explanations for every problem

📊

Progress Analytics

Track your mastery across all topics

🚫

Ad-Free Learning

Focus on math without distractions

No credit card required • Cancel anytime

More Questions

Click on any question to see the complete solution with step-by-step explanations