+0  
 
+6
1059
4
avatar+209 

lim x → −∞ 4ex = 0

 

lim x → ∞ 2ex = ∞ 

Can someone explain why?

 Jan 31, 2016

Best Answer 

 #2
avatar+129845 
+15

I assume that the first one is :

 

lim x → −∞ 4e^x = 0

 

Note that, as x  → −∞, e^x will grow smaller and smaller.....and if we let x assume some large negative value, e^x, will approach 0

 

Therefore,

lim x → −∞ 4e^x = 0

 

 

Likewise, I assume that the second one is :

 

lim x → ∞ 2e^x = ∞

 

Again, if we let x approach some large positive value, e^x will grow larger and larger. So, as x → ∞ , e^x  will also approach ∞

 

Here's the graph of e^x that will give you some idea of the end behaviors of both functions :

 

https://www.desmos.com/calculator/ml0aj0en2z

 

 

 

cool cool cool

 Jan 31, 2016
 #1
avatar+8262 
+10

I will try to help.

 

Lim x → −∞ 4e^x=0 
because you can change it to look like 
Lim x → ∞ 4/e^x 
Then the denominator gets big so it goes to zero

 

But listen to the BIG BOSS first. I am trying to help, so I may be incorrect. CPhill, the class genius, will tell you the answer, and maybe correct me.

 Jan 31, 2016
edited by DragonSlayer554  Jan 31, 2016
edited by DragonSlayer554  Jan 31, 2016
edited by DragonSlayer554  Jan 31, 2016
 #2
avatar+129845 
+15
Best Answer

I assume that the first one is :

 

lim x → −∞ 4e^x = 0

 

Note that, as x  → −∞, e^x will grow smaller and smaller.....and if we let x assume some large negative value, e^x, will approach 0

 

Therefore,

lim x → −∞ 4e^x = 0

 

 

Likewise, I assume that the second one is :

 

lim x → ∞ 2e^x = ∞

 

Again, if we let x approach some large positive value, e^x will grow larger and larger. So, as x → ∞ , e^x  will also approach ∞

 

Here's the graph of e^x that will give you some idea of the end behaviors of both functions :

 

https://www.desmos.com/calculator/ml0aj0en2z

 

 

 

cool cool cool

CPhill Jan 31, 2016
 #3
avatar+209 
+5

Yes, sorry for the typo...copy and paste messed it up. Thank you both, I understand it perfectly now :)

 Jan 31, 2016
 #4
avatar+8262 
+5

You are very welcome! Ask your questions,if you are confused. We can help again!

 

(CPhill might get angry!)

 

Well, thanks for the +5 points!

 Jan 31, 2016

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