The roots of the function f(x) = x² - 2x - 3 are shown. What is the missing number? 
x = -1 and x = 

Solution:

f(x) = x² - 2x - 3

In order to find the roots, equate the function to zero

x² - 2x - 3 = 0

Now group the terms which have the same variable and move the constant to the other side

x² - 2x - 3 = 0

Balance the equation by adding a constant on each side

x² - 2x + 1 = 3 + 1

x² - 2x + 1 = 4

The equation can be rewritten as perfect squares.

(x - 1)² = 4

Taking square root on both sides

x - 1 = ±2

x = 1 ± 2

So we get,

x = 1 + 2 = 3

x = 1 - 2 = -1

Therefore, the missing number is 3.

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The roots of the function f(x) = x² - 2x - 3 are shown. What is the missing number? 
x = -1 and x = 

Summary:

The roots of the function f(x) = x² - 2x - 3 are shown. The missing number is 3.