Finding the Zeros of a Parabola

🏆Practice zeros of a fuction

Finding the zeros of a quadratic function of the form \(y=ax^2+bx+c\)

Zero points of a function are its intersection points with the XX-axis.
To find them, we set Y=0 Y=0 ,
we get an equation that can sometimes be solved using a trinomial or the quadratic formula.

When trying to find the zero point, you can encounter three possible results:

  1. Two results -
    In this case, the function intersects the XX-axis at two different points.
  2. One result -
    In this case, the function intersects the XX-axis at only one point, meaning the vertex of the parabola is exactly on the XX-axis.
  3. No results -
    In this case, the function does not intersect the XX-axis at all, meaning it hovers above or below it.
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Test yourself on zeros of a fuction!

einstein

The following function has been graphed below:

\( f(x)=-x^2+5x+6 \)

Calculate points A and B.

BBBAAACCC

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Zero points describe a situation where the function equals zero.

Let's look at an example:
We have the function
X24x+5X^2-4x+5
We substitute into the quadratic formula and get:

4±(4)241521=4±42 {-4 \pm \sqrt{(-4)^2-4*1*5} \over 21}=-\frac{4\pm\sqrt{-4}}{2}

This equation has no solution because the delta inside the root is negative. Therefore, this equation never equals zero, it hovers above the X-axis, and it has no zero points.

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Examples with solutions for Zeros of a Fuction

Exercise #1

The following function has been graphed below:

f(x)=x2+5x+6 f(x)=-x^2+5x+6

Calculate points A and B.

BBBAAACCC

Video Solution

Step-by-Step Solution

To solve for the x-intercepts of the function f(x)=x2+5x+6 f(x) = -x^2 + 5x + 6 , we will find the roots of the quadratic equation x2+5x+6=0 -x^2 + 5x + 6 = 0 .

Let's attempt to factor this quadratic equation first. Rewrite the equation as follows:

x2+5x+6=0 -x^2 + 5x + 6 = 0 .

To factor, we look for two numbers that multiply to 6-6 (the product of aa and cc, where a=1a = -1 and c=6c = 6) and add to 55 (the middle coefficient bb).

The numbers that satisfy this condition are 1-1 and 66.

Thus, the quadratic can be factored as:

(x6)(x+1)=0(x - 6)(x + 1) = 0.

Setting each factor equal to zero gives us:

x6=0x - 6 = 0 or x+1=0x + 1 = 0.

Solving these equations, we find:

x=6x = 6 and x=1x = -1.

Thus, the points A and B, the x-intercepts of the function, are:

(1,0)(-1, 0) and (6,0) (6, 0).

Therefore, the solution to the problem is (1,0),(6,0)(-1, 0), (6, 0).

Answer

(1,0),(6,0) (-1,0),(6,0)

Exercise #2

The following function has been graphed below:

f(x)=x26x+5 f(x)=x^2-6x+5

Calculate points A and B.

AAABBB

Video Solution

Step-by-Step Solution

To solve for the points A and B, we need to find the roots of the function f(x)=x26x+5 f(x) = x^2 - 6x + 5 where f(x)=0 f(x) = 0 .

Let's proceed step-by-step:

  • Step 1: Set the function to zero
    We begin by setting the equation to zero: x26x+5=0 x^2 - 6x + 5 = 0 .
  • Step 2: Factor the quadratic
    We need to factor the expression. We look for two numbers that multiply to c=5 c = 5 and add to b=6 b = -6 . These numbers are 1-1 and 5-5.
  • Step 3: Write the factorization
    Therefore, we can write the quadratic as: (x1)(x5)=0(x - 1)(x - 5) = 0.
  • Step 4: Solve for the roots
    Set each factor equal to zero: \begin{align*} x - 1 &= 0 \\ x &= 1 \end{align*} \begin{align*} x - 5 &= 0 \\ x &= 5 \end{align*} The roots are x=1 x = 1 and x=5 x = 5 .
  • Step 5: Identify the Points A and B
    The points A and B, where the function intersects the x-axis, are (1,0)(1, 0) and (5,0)(5, 0).

Thus, the coordinates of points A and B are (1,0),(5,0) (1,0),(5,0) , which matches choice 1.

Answer

(1,0),(5,0) (1,0),(5,0)

Exercise #3

The following function has been graphed below:

f(x)=x28x+16 f(x)=x^2-8x+16

Calculate point A.

AAACCC

Video Solution

Step-by-Step Solution

Let's solve the problem by following the outlined analysis:

  • Step 1: Identify important points on the parabola.
  • Step 2: Calculate the y-intercept by evaluating f(0) f(0) .
  • Step 3: Confirm understanding of the vertex form and its characteristics.

Step 1: Identify the significant points on the function.
The function given is f(x)=x28x+16 f(x) = x^2 - 8x + 16 .

This function can be seen as
f(x)=(x4)2 f(x) = (x - 4)^2 .

This format not only indicates it is always non-negative but also reveals the vertex is located at x=4 x = 4 , importantly, with f(x)=0 f(x) = 0 .

Step 2: Calculate the y-intercept.
Evaluate the function at x=0 x = 0 :

f(0)=0280+16=16 f(0) = 0^2 - 8 \cdot 0 + 16 = 16 .
So, the y-intercept is (0,16) (0, 16) .

Thus, point A, which is often labeled at a crucial intercept, corresponds to the y-intercept of the function. The calculation confirms that point A is (0,16) (0, 16) .

Therefore, the solution to the problem is (0,16) (0,16) .

Answer

(0,16) (0,16)

Exercise #4

The following function has been plotted on the graph below:

f(x)=x28x+16 f(x)=x^2-8x+16

Calculate point C.

CCC

Video Solution

Step-by-Step Solution

To solve the exercise, first note that point C lies on the X-axis.

Therefore, to find it, we need to understand what is the X value when Y equals 0.

 

Let's set the equation equal to 0:

0=x²-8x+16

We'll use the preferred method (trinomial or quadratic formula) to find the X values, and we'll discover that

X=4

 

Answer

(4,0) (4,0)

Exercise #5

The following function has been graphed below:

f(x)=x23x4 f(x)=x^2-3x-4

Calculate points A and B.

CCCAAABBB

Video Solution

Step-by-Step Solution

To solve for points A and B, we find the x-intercepts of the function by setting:

f(x)=x23x4=0 f(x) = x^2 - 3x - 4 = 0

We check if it can be factored:

Factor x23x4 x^2 - 3x - 4 . The factors of -4 that add to -3 are -4 and 1.

Thus, factor the function as (x4)(x+1)=0 (x - 4)(x + 1) = 0 .

Set each factor to zero:

  • x4=0 x - 4 = 0 implies x=4 x = 4
  • x+1=0 x + 1 = 0 implies x=1 x = -1

These are the x-intercepts, or roots, of the quadratic function.

Therefore, the coordinates of points A and B, where the function intersects the x-axis, are A(1,0) A(-1, 0) and B(4,0) B(4, 0) .

The correct choice corresponding to these points is option 3: A(1,0),B(4,0) A(-1,0), B(4,0) .

Thus, the solution to the problem is A(1,0),B(4,0) A(-1,0), B(4,0) .

Answer

A(1,0),B(4,0) A(-1,0),B(4,0)

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