CHO XLIM A X 1 2017 12X 2018 2+ ; XLIM( X2 BX 1 X) 2→−∞→+∞ + + − = ....

Câu 28: Cho

x

lim a x 1 2017 1

2

x 2018 2+ ;

x

lim

(

x

2

bx 1 x

)

2

→−∞

→+∞

+ + − = . Tính P 4a b= + .A. P 3= . B. P= −1. C. P 2= . D. P 1= .