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OpenStudy (anonymous):
any body help me how to solve lim x->0 (sin4x)/x
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hartnn (hartnn):
follow your last post.
OpenStudy (anonymous):
i cant understand how>?
hartnn (hartnn):
do u know this standard limit :
\(\lim \limits_{x \rightarrow0}\frac{\sin x}{x}=1\)
OpenStudy (anonymous):
yes i konw that
OpenStudy (anonymous):
i cant use l hospital rules
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OpenStudy (anonymous):
in my book answer is 4
i dont know how??
hartnn (hartnn):
so, do this , multiply the numerator and denominator by 4
\(\huge 4\lim \limits_{x \rightarrow0}\frac{\sin 4x}{4x}=...?\)
hartnn (hartnn):
\(\huge 4\lim \limits_{4x \rightarrow0}\frac{\sin 4x}{4x}=...?\)
now put 4x = y
and you get a standard limit whose value is 1 (with 4)
OpenStudy (anonymous):
if i multiply that what did i got?
OpenStudy (anonymous):
\[\lim_{x \rightarrow 0} \sin\] i got
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hartnn (hartnn):
what! ? how ??
OpenStudy (anonymous):
can you give me full steps:
hartnn (hartnn):
let y=4x
\(\large 4\lim \limits_{4x \rightarrow0}\frac{\sin 4x}{4x}=4[\lim \limits_{y \rightarrow0}\frac{\sin y}{y}]= 4(..?..)\)
OpenStudy (anonymous):
1you mean?
hartnn (hartnn):
yes, ?=1
so, 4*1=4
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OpenStudy (anonymous):
\[4\lim4x→0\sin4x4x=4[limy→0sinyy]=4(1)= than is equal \to 4\]
OpenStudy (anonymous):
thank you soo much
hartnn (hartnn):
hmm...welcome ^_^
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