2.1.50 Calculation of Limits

Condition: Find the limits of functions without using the rule of the Lotal. a) \ (\ lim _ {x \ rishtarrow \ infty} \ frac {(7-x)^{4}-(9-x)^{4}} {(2-x)^{3}-(1+x) {3}} \) \ (\ lim _ {x \ Rightarrow 1} \ Frac {2 x^{2} -x-1} {x^{3} +2 x^{2} -x-2} \) \ b) \ (\ lim {x \ rightarRown 0} {\ cos 2 x-1} {x \ tan 3 x} \), g) \ (\ lim _ {x \ rightarrow 0} \ frac {6^{2 x} -7^{-2 x}}} {\ sin 3 x-2 x} \) \ (\ lim _ {x \ rightarrow \ infty} \ left (\ frac {10 x+2} {10 x-7} \ right)^{x-3} \).