Can you guys help me with my home work? A random polynomial P(x) is given. When the limit of P(x)/[x 2-4] tends to infinity it equals 4 when it tends to 2 it equals 9/4. I gotta find the polynomial P(x).
X 2 is supused to be square x
And in the last lim of the pic it's supposed to tends 2 not infinite
The numerator has a 4x^2 term
>>8431710
Why?
>>8431721
Because of the limit to infinity. It means that at infinity, the limit is equivalent to 4x^2 / x^2 which then is equal to 4.
Not only do you know it has a 4x^2 term, you also know that is the leading term because if it has a bigger term (like an x cubed) then the limit would diverge to infinity.
>>8431696
You can factor the denominator into (x-2)(x+2), what does that mean for the convergence at x=2 and P(x)?
>>8431732
I somehow got to simplify x-2
>>8431727
Oh thanks my dude now i undrstand
>>8431732
It should be like something*(x-2) and that something for P(2) should be 9
Lim x -> inf of P(x) / (x^2 - 4) = K
Apply Lhopitals rule twice and reason P(x) has to be polynomial of degree 2.
P(x) = Ax^2 + Bx + C
P'(x) = 2Ax + B
P''(x) = 2A
x^2 - 4
2×
2
2A/2 = K
A = K
SO P(x) = Kx^2 + Bx + C where B and C can be any number you want.
>>8431752
I know it's degree is 2 by now but i am asked what's the polynomial P(x)
>>8431696
>Can you guys help me with my home work?
no
P(x) = Kx^2 + Bx + C where B and C can be any number you want.
K is the number the limit is equal to.
Ok thx guys you are the best i've solved it