f(x)= (2x − 2) / (x² + x − 2)
I have vertical asymptote @ x=-2
horizontal asymptote @ y=0
how can i justify my answer using limits?
I have vertical asymptote @ x=-2
horizontal asymptote @ y=0
how can i justify my answer using limits?
-
f(x)=(2x-2)/(x²+x-2)
the vertical asymptotes occur when
the denominator is 0:
x²+x-2=0
(x+2)(x-1)=0
x=-2 and x=1
But notice that x=1 is a HOLE!
by plugging x=1 you'll get a 0/0 form.
so the only vertical asymptote is x=-2
--------------------
for the horizontal asymptotes,you need
to find the limit as x approaches infinity and minus infinity.
lim (2x-2)/(x²+x-2)
x->∞
lim 2(x-1)/(x-1)(x+2)
x->∞
lim 2/(x+2)
x->∞
as lim x->∞ then 2/(∞+2) =2/∞ = 0
for x->-∞ the limit is also 0
so the horizontal asymptote is y=0
the vertical asymptotes occur when
the denominator is 0:
x²+x-2=0
(x+2)(x-1)=0
x=-2 and x=1
But notice that x=1 is a HOLE!
by plugging x=1 you'll get a 0/0 form.
so the only vertical asymptote is x=-2
--------------------
for the horizontal asymptotes,you need
to find the limit as x approaches infinity and minus infinity.
lim (2x-2)/(x²+x-2)
x->∞
lim 2(x-1)/(x-1)(x+2)
x->∞
lim 2/(x+2)
x->∞
as lim x->∞ then 2/(∞+2) =2/∞ = 0
for x->-∞ the limit is also 0
so the horizontal asymptote is y=0
-
You dont really use limits to find a vertical asymptote although you could take the limit as x-->-2+ and -2-
to figure out whether itll be tending towards negative or positive infinity.
for horizontal asymptote you take the limit as x-->∞ and -∞
but in this case since its a polynomial, we can only go with 1 as it will be the same on the other side.
lim x-->∞ (2x/x^2)
lim x-->∞ (2/x) = 0
to figure out whether itll be tending towards negative or positive infinity.
for horizontal asymptote you take the limit as x-->∞ and -∞
but in this case since its a polynomial, we can only go with 1 as it will be the same on the other side.
lim x-->∞ (2x/x^2)
lim x-->∞ (2/x) = 0
-
f(x) = 2(x - 1)/(x + 2)(x - 1) = 2/(x + 2)
Hence, vertical asymptote at x = -2 and horizontal asymptote at y = 0
as x ---> -2 from the negative side, x + 2 ---> -0.00000000.....2/(x + 2) ---> - ∞
as x ---> -2 from the positive side, x + 2 ---> 0.000000000....2/(x + 2) ---> + ∞
:)>
Hence, vertical asymptote at x = -2 and horizontal asymptote at y = 0
as x ---> -2 from the negative side, x + 2 ---> -0.00000000.....2/(x + 2) ---> - ∞
as x ---> -2 from the positive side, x + 2 ---> 0.000000000....2/(x + 2) ---> + ∞
:)>