Kathy P. answered 03/03/21
Mechanical Engineer with 10+ years of teaching and tutoring experience
Given: y = (x^2 - 5x - 6) / (x^2 + 5x + 4)
Find: VA, End behavior, intercepts, domain
Solution:
y = (x^2 - 5x - 6) / (x^2 + 5x + 4)
y = [(x + 1)(x - 6)] / [(x + 1)(x + 4)]
y = (x - 6) / (x + 4). HOLE at x = -1
VA: x = -4
HA: y = 1
When: x = -1
y = (-1 - 6) / (-1 + 4)
y = (-7) / (3)
Hole at point: (-1, -7/3)
End Behavior is determined by HA
As x approaches +/- infinity, y approaches 1
X-intercept ==> y = 0
y = (x - 6) / (x + 4)
0 = (x - 6) / (x + 4)
0 = x - 6 Numerator must be zero
6 = x
X-intercept at point (6,0)
y-intercept ==> x = 0
y = (x - 6) / (x + 4)
y = (0 - 6) / (0 + 4)
y = (-6)/(4) = -3/2
Y-intercept at point (0, -3/2)
Domain:
Skip over values of x that make the denominator = 0
or where the function is not defined (e.g. the hole)
The domain is valid values of x.
Note: x is NOT equal to -1 or 4
Domain: (-infinity, -1) U (-1, 4) U (4, infinity)