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x tends to 0 ((3+2x)^5-243)/(3x)

 Aug 1, 2016
 #1
avatar+33653 
0

See reply #3 to your original post.

 Aug 1, 2016
 #2
avatar+26388 
+5

x tends to 0 ((3+2x)^5-243)/(3x)

 

\(\begin{array}{|rcll|} \hline && \lim \limits_{x\to 0} { \left( \frac{ (3+2x)^5-243 } {3x} \right) } \\\\ &=& \lim \limits_{x\to 0} { \left( \frac{ \binom{5}{0}3^5+ \binom{5}{1}3^4(2x)+ \binom{5}{2}3^3(2x)^2+ \binom{5}{3}3^2(2x)^3+ \binom{5}{4}3(2x)^4+ \binom{5}{5}(2x)^5 -243 } {3x} \right) }\\\\ &=&\lim \limits_{x\to 0} { \left( \frac{ 3^5+ \binom{5}{1}3^4(2x)+ \binom{5}{2}3^3(2x)^2+ \binom{5}{3}3^2(2x)^3+ \binom{5}{4}3(2x)^4+ \binom{5}{5}(2x)^5 -3^5 } {3x} \right) }\\\\ &=&\lim \limits_{x\to 0} { \left( \frac{ \binom{5}{1}3^4(2x)+ \binom{5}{2}3^3(2x)^2+ \binom{5}{3}3^2(2x)^3+ \binom{5}{4}3(2x)^4+ \binom{5}{5}(2x)^5 } {3x} \right) }\\\\ &=&\lim \limits_{x\to 0} { \left( ~ \binom{5}{1}3^3\cdot 2+ \binom{5}{2}3^2\cdot 4x+ \binom{5}{3}3^1\cdot 8x^2+ \binom{5}{4}16x^3+ \binom{5}{5}\frac{32}{3}x^4 ~ \right) }\\\\ &=& \binom{5}{1}3^3\cdot 2 \\\\ &=& 5\cdot 27 \cdot 2 \\\\ &=& 270 \\\\ \hline \end{array}\)

 

laugh

 Aug 1, 2016

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