Question:
Let f(x) = x^2 - 3x + 2
and g(x) = 2x - 4
be two functions defined on the closed interval [0, 3]
.
Find the x-coordinate(s) of the point(s) of intersection of f(x)
and g(x)
.
Determine the area enclosed between the graphs of f(x)
and g(x)
on the interval [0, 3]
.
Answer:
To find the x-coordinate(s) of the point(s) of intersection, we need to set f(x) = g(x)
and solve for x
.
Setting x^2 - 3x + 2 = 2x - 4
, we have:
x^2 - 5x + 6 = 0
Factoring the quadratic equation, we get:
(x - 2)(x - 3) = 0
Therefore, x - 2 = 0
or x - 3 = 0
.
Solving each equation, we find that x = 2
or x = 3
.
Thus, the point(s) of intersection are (2, f(2))
and (3, f(3))
.
To find the area enclosed between the graphs of f(x)
and g(x)
, we need to find the definite integral of |f(x) - g(x)|
over the interval [0, 2]
and add it to the definite integral of |g(x) - f(x)|
over the interval [2, 3]
.
The absolute difference between f(x)
and g(x)
is given by |f(x) - g(x)|
:
|f(x) - g(x)| = |(x^2 - 3x + 2) - (2x - 4)|
= |x^2 - 3x + 2 - 2x + 4|
= |x^2 - 5x + 6|
Therefore, the area enclosed between the graphs of f(x)
and g(x)
is:
A = ∫[0, 2] |f(x) - g(x)| dx + ∫[2, 3] |g(x) - f(x)| dx
Evaluating the first integral, we have:
∫[0, 2] |x^2 - 5x + 6| dx = ∫[0, 2] (x^2 - 5x + 6) dx (since the integrand is non-negative on [0, 2])
= ∫[0, 2] (x^2 - 5x + 6) dx
= [x^3/3 - (5x^2)/2 + 6x] |[0, 2]
= [2^3/3 - (5(2)^2)/2 + 6(2)] - [0^3/3 - (5(0)^2)/2 + 6(0)]
= 8/3 - 20/2 + 12 - 0/3 + 0 + 0
= 8/3 - 20/2 + 12
= (-32 + 60 - 72)/6
= (-44)/6
= -22/3
Evaluating the second integral, we have:
∫[2, 3] |x^2 - 5x + 6| dx = ∫[2, 3] (5x - x^2 - 6) dx (since the integrand is non-negative on [2, 3])
= ∫[2, 3] (5x - x^2 - 6) dx
= [5x^2/2 - (x^3)/3 - 6x] |[2, 3]
= [3^3/2 - (3(3)^2)/3 - 6(3)] - [2^3/2 - (2(2)^2)/3 - 6(2)]
= 27/2 - 27/3 - 18 - 8/2 + 8/3 + 12
= (54 - 54 - 108 - 16 + 16 + 36)/6
= (-128)/6
= -64/3
Adding both integrals together, we get:
A = -22/3 + (-64/3) = -86/3
The area enclosed between the graphs of f(x)
and g(x)
on the interval [0, 3]
is therefore -86/3
square units.