Question

e^2x-7e^x+10=0
Show all steps

Answer 1

Hint:

(e^x)^2 - 7e^x + 10 = 0

Let e^x = u

u^2 - 7u + 10 = 0

Answer 2

How did you turn it into a u?

Answer 3

That hint didn't help

Answer 4

u^2 - 7u + 10 = 0 is u = 2,5

But the answer for e^2x-7e^x+10=0 is x = -1.0074 and x = 0.83

Answer 5

I give obvious hints and students are still clueless.

Answer 6

let \[e^x=u\]
so\[(e^x)^2-7e^x+10\]
very obvious
how would you substitute for u

Answer 7

That's because you did it wrong bro @YesterdayiSaidTomorow

Answer 8

So... I raise the answers of u^2 - 7u + 10 = 0 to the second power? I don't get what you're saying

Answer 9

You're supposed to factor u^2 -7u + 10 to get

(u - 5)(u - 2) = 10

Then re-write as:

u - 5 = 0
u - 2 = 0

Then RE-SUBSTITUTE e^x back in:

e^x - 5 = 0
e^x - 2 = 0

Now continue solving for x:

Answer 10

ooooo

Answer 11

can you finish it to ensure I get the right answer?

Answer 12

Nope. You already have the answers. Figure it out bro.

Answer 13

damn

Answer 14

fiesty

Answer 15

Lol, but I got log(5)

Answer 16

and log(2)

Answer 17

ln

Answer 18

???

Answer 19

you dont use log for e,log is for base10 ln is for base e

Answer 20

Ugh I don't know how to do this at all

Answer 21

\[x=\ln(5) ,x=\ln(2)\]

Answer 22

but that doesn't match http://www.wolframalpha.com/input/?i=e%5E2x-7e%5Ex%2B10%3D0

Answer 23

Yeah, just use ln(5) and ln(2)

Answer 24

that 1.6 and the other is -1.0074?

Answer 25

Yahoo Answers said the same thing, so whatever and thank you!

Answer 26

I get:

ln(5) = 1.60944
ln(2) = 0.693147