ln

[Bulk]

just a quickie (really liking this thread for homework help)
i had a maths problem in my homework where part of the question was simplyfy:  y=e^0.5a + x

i simplified it to

ln(y) = 0.5a + x
ln(y) -0.5a = x

but the back of the book says it was wrong, where did i go wrong?

[Goalie]

Did you take the natural log of x?

[Bulk]

no, what's that?

[Goalie]

That's what "ln" stands for.  It's the natural log.  Log_e is written as ln.

I saw you took the ln of y and of -0.5a.  But I don't see that you took the ln of x.

[Bulk]

ohhhh i see

i read it as y=e^(0.5a + x)

but it's actually
y=e^((0.5a) + x)


thanks goalie

[Goalie]

It's always those little things that you don't see.

No worries.

[jim360]

ohhhh i see

i read it as y=e^(0.5a + x)

but it's actually
y=e^((0.5a) + x)


thanks goalie

Those two say exactly the same. I'm assuming that you read it as y= e^x+a/2 when it should be y= x + e^a/2.

In the first case lny =x+0.5a as you said, in the second case start by taking x to the left-hand side of the equation, y-x=e^0.5a, and then take natural logs of both sides.