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21. (a) Find lim x  x  2 5x .
x
x   4, x  1


22. Given   x   , A 1 x  B , where A and B are constants.
f
 x  1, x 
 B
f
(i) Find the values of A and B if the limit of   x exist at x  1 and x  B .
 
(ii) Hence, find lim f x .
x 6
23. A function is defined as


 3 x
 2x  2 7x  3 , x  3

 , m x  3
 x


f   x   n  , 3 x 
5
 7
 x  7
 , 5  x  7
 x  7
 p  2, x  7


Where m, n and pare constants.

 
(a) Find lim f x
x 3 

(b) Determine the values of and such that lim f x    f   3  lim f   x
x  3  x  3 

 
(c) Find the values of such that lim f x  lim f   x
x  7  x  7 

ANSWERS

1. (a) 3 (b) 0
1
2. (a) 3 (b)
3