Quadratic function - x-intercepts?

In summary, the conversation involves finding the x-intercepts for the function f(x) = -2x^2 + 12x + 12 and determining whether the quadratic formula is needed to solve for them. The speaker has expressed the function in standard form and found the maximum value, but is unsure about the next steps. The expert suggests using the quadratic formula or completing the square to solve for the x-intercepts, as the function does not seem to factorize.
  • #1
Agent_J
13
0
f(x) = -2x^2 + 12x + 12

I was able to express it in standard form and find the maximum value, but I can't seem to get the x-intercepts

I got -2x^2 + 12x + 12 = 0
-2 (x^2 - 6x + 6) = 0

does that mean I need to use the quadratic formula or did I do something wrong?
 
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  • #2
There is a Homework help zone. But you have:

-2 (x^2 - 6x + 6) = 0

If a product equals 0 at least one of the bits of the product must equal 0. So either:

-2 = 0

or:

x^2 - 6x + 6 = 0

I think we can safely assume that -2 does not equal 0. So now you can solve:

x^2 - 6x + 6 = 0

By using the quadratic equation or completing the square (although it would have been just as easy to use the quadratic equation on -2x^2 + 12x + 12) I'm fairly sure this does not factorise.
 
  • #3


Yes, to find the x-intercepts of a quadratic function, you can use the quadratic formula or factor the equation. In this case, factoring would be the easier option since the coefficient of x^2 is -2, which is not a prime number. So, you can rewrite the equation as -2(x^2 - 6x + 6) = 0 and then factor the quadratic expression inside the parentheses. This will give you two values of x, which will be the x-intercepts of the function. Alternatively, you can use the quadratic formula, which will also give you the same values for x. Just make sure to double check your work and plug in the values of x into the original equation to confirm that they are indeed the x-intercepts.
 

1. What are x-intercepts in a quadratic function?

X-intercepts, also known as roots or solutions, are the points where a quadratic function intersects the x-axis. These points represent the values of x where the function crosses or touches the x-axis. They are also the points where the y-value of the function is equal to 0.

2. How do you find the x-intercepts of a quadratic function?

To find the x-intercepts of a quadratic function, you can use the quadratic formula or factor the function. The quadratic formula is x = (-b ± √(b² - 4ac)) / 2a, where a, b, and c are the coefficients of the quadratic function in the form ax² + bx + c. Factoring involves finding two numbers that when multiplied, equal the constant term (c) and when added, equal the coefficient of the linear term (b). These numbers will be the x-intercepts of the function.

3. Can a quadratic function have more than two x-intercepts?

No, a quadratic function can have a maximum of two x-intercepts. This is because a quadratic function is a polynomial of degree 2, meaning it has an exponent of 2. Therefore, the graph of a quadratic function is a parabola, which can intersect the x-axis at a maximum of two points.

4. What does it mean if a quadratic function has no x-intercepts?

If a quadratic function has no x-intercepts, it means that the parabola does not intersect the x-axis. This could happen if the function has a constant value (c) that is not equal to 0, resulting in a parabola that is always above or below the x-axis. In this case, the function has no real solutions.

5. How do x-intercepts relate to the roots of a quadratic equation?

X-intercepts and roots of a quadratic equation are the same thing. They represent the points where the function crosses or touches the x-axis and the values of x where the function is equal to 0. In other words, the x-intercepts are the solutions to the quadratic equation, which can be found by setting the function equal to 0 and solving for x.

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