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What are the zeroes of f(x) = x2 − 2x − 3? x = −3, 1 x = −3, −1 x = 3, 1 x = 3, −1

Question

What are the zeroes of

f(x) = x² − 2x − 3?

  • x = −3, 1
  • x = −3, −1
  • x = 3, 1
  • x = 3, −1
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Solution

1. Break Down the Problem

We need to find the zeroes of the function f(x)=x22x3 f(x) = x^2 - 2x - 3 . This means we need to solve the equation f(x)=0 f(x) = 0 .

2. Relevant Concepts

To find the zeroes of the quadratic function, we can use the quadratic formula: x=b±b24ac2a x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} where a=1 a = 1 , b=2 b = -2 , and c=3 c = -3 .

3. Analysis and Detail

Let's apply the quadratic formula step by step:

  1. Calculate the discriminant: b24ac=(2)24(1)(3)=4+12=16 b^2 - 4ac = (-2)^2 - 4(1)(-3) = 4 + 12 = 16

  2. Substitute the values into the quadratic formula: x=(2)±1621=2±42 x = \frac{-(-2) \pm \sqrt{16}}{2 \cdot 1} = \frac{2 \pm 4}{2}

  3. Solve for the two possible values of x x :

    • First solution: x1=2+42=62=3 x_1 = \frac{2 + 4}{2} = \frac{6}{2} = 3
    • Second solution: x2=242=22=1 x_2 = \frac{2 - 4}{2} = \frac{-2}{2} = -1

4. Verify and Summarize

The solutions we found are x=3 x = 3 and x=1 x = -1 . Both values can be verified by substituting back into the original function f(x) f(x) :

  • For x=3 x = 3 : f(3)=322(3)3=963=0 f(3) = 3^2 - 2(3) - 3 = 9 - 6 - 3 = 0
  • For x=1 x = -1 : f(1)=(1)22(1)3=1+23=0 f(-1) = (-1)^2 - 2(-1) - 3 = 1 + 2 - 3 = 0

Thus, both values are indeed zeroes of the function.

Final Answer

The zeroes of the function f(x)=x22x3 f(x) = x^2 - 2x - 3 are x=3 x = 3 and x=1 x = -1 .

This problem has been solved

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