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jawab

15. 
limit(x-> 5)  (x² - 2)(√(x²-9) + 4))/ (√(x²- 9)- 4)(√(x²-9) + 4))

limit (x -> 5)  (x²-25) (√(x²-9) + 4) / (x² -25)

limit(x-> 5) √(x²-9) + 4  
x = 5 
limit = √(25-9) + 4 = √16 + 4 = 4 + 4=  8

16.
limit (x -> 1)  ( x +1)(x  -  3)/(x +1)
limit(x > 1)  ( x- 3)
x = 1 --> limit = 1 - 3 = - 2