1. The function f(x)=(x^24x5)/(x+1) is defined everywhere except at x = 1. If po
ID: 2872577 • Letter: 1
Question
1. The function f(x)=(x^24x5)/(x+1) is defined everywhere except at x = 1. If possible, define f (x) at 1 so that it becomes continuous at 1.
a) f(1)=5
b) f(1)=0
c) Not possible because there is an infinite discontinuity at the given point.
d) Not possible because there is a jump discontinuity at the given point.
e) f(1)=6
2. Give the values of A and B for the function f(x) to be continuous at both x = 1 and x = 2.
f(x)=AxB -->x1, 1x --> 1<x<2, Bx^2A --> x2
a) A = 1 and B = 1
b) A = 3 and B = 1
c) A = 2 and B = 0
d) A = 2 and B = 2
e) A = 2 and B = 1
Explanation / Answer
1. Lets find the limit of f(x) at x=-1
lim(x-->-1) (x^24x5)/(x+1) =lim(x-->-1) (x+1)(x-5)/(x+1) =lim(x-->-1) (x-5) =-1-5= -6
As the limit exists we can make it continous by defining f(-1)=-6
e.
2. If f(x) is continous at x=1 then
A*1-B=-1*1
A-B= -1 equation (1)
If f(x) is continous at x=2 then
-1*2=B*2^2-A
-2=4B-A equation (2)
From equation 1 and 2 we get
3B=-3
B=-1
A-B=-1
A-(-1)=-1
A+1=-1
A=-2 and B=-1
e.
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