To sketch the graph we have to solve the function with each value of x to get the coordinates.
f(x) = x² − 4x − 5
−2 ≤ x ≤ 6
This inequality represents the domain for x. Therefore x is greater than equal to -2 but less than equal to 6.
The range of x is as follows:
x = -2, -1, 0, 1, 2, 3, 4, 5, 6
We already have the values for x therefore, we must substitute the values of x into the function f(x) = x² − 4x − 5 to find the y values.
Solutions:
For x = -2
f(x) = x² − 4x − 5
= -2² − 4(-2) - 5
= 4 + 8 - 5
= 7
Point = (-2,7)
For x = -1
f(x) = x² − 4x − 5
= -1² - 4(-1) - 5
= 1 + 4 - 5
= 0
Point = (-1,0)
For x = 0
f(x) = x² − 4x − 5
= 0² - 4(0) - 5
= 0 - 0 - 5
= -5
Point = (0,-5)
For x = 1
f(x) = x² − 4x − 5
= 1² - 4(1) - 5
= 1 - 4 - 5
= -8
Point = (1,-8)
For x = 2
f(x) = x² − 4x − 5
= 2² - 4(2) - 5
= 4 - 8 - 5
= -9
Point = (2,-9)
For = 3
f(x) = x² − 4x − 5
= 3² - 4(3) - 5
= 9 - 12 - 5
= -8
Point = (3,-8)
For x = 4
f(x) = x² − 4x − 5
= 4² - 4(4) - 5
= 16 - 16 - 5
= -5
Point = (4,-5)
For x = 5
f(x) = x² − 4x − 5
= 5² - 4(5) - 5
= 25 - 20 - 5
= 0
Point = (5,0)
For x = 6
f(x) = x² − 4x − 5
= 6² - 4(6) - 5
= 36 - 24 - 5
= 7
Point = (6,7)
Coordinates for graph = (-2,7) , (-1,0) , (0,-5) , (1,-8) , (2,-9) , (3,-8) , (4,-5) , (5,0) , (6,7)
These are the points to sketch the quadratic graph.
