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comment Working out rent?
It's probably to the landlord's benefit that differential equations don't need to be solved in order to determine rent...
May
18
awarded  Popular Question
Mar
22
revised Can't Get Present Value Answer?
added 21 characters in body
Mar
22
answered Can't Get Present Value Answer?
Mar
22
comment Can't Get Present Value Answer?
My only other pieces of advice are to make sure you are using the correct interest rate, and double checking your formula. 8% compounded quarterly is 2% effective quarterly, and I've never seen present value described as you have laid it out (see e.g. wikipedia)
Mar
22
comment Can't Get Present Value Answer?
Well then, it certainly seems as if the issue is that you are using the formula as directed instead of understanding how and why such a formula exists. I suggest writing down a cash flow diagram, the associated present value of the payments, and realizing you're summing a geometric series.
Mar
22
comment Can't Get Present Value Answer?
Can you tell us what you did 1 or 2 of those 20 times? If you understand how an annuity is calculated, the solution is immediate, this isn't a tricky problem.
Mar
22
revised Can't Get Present Value Answer?
corrected tags
Mar
1
comment Properties of a transpose
I'd use induction, and the property $(AB)^T = B^T A^T$
Mar
1
comment Properties of a transpose
You don't know A is invertible, so how will the property you listed help you?
Feb
28
comment why and when t0 use norm instead of abs and vice versa
the absolute value has a specific definition. the norm can have multiple definitions, depending on context. the absolute value is a norm, but a norm is not necessarily an absolute value. You might even see people "abuse notation" and use the absolute value bars in place of norm bars.
Feb
28
comment Significance of orthonormal basis in wavelet analysis
mathoverflow.net/questions/42040/…
Feb
22
comment YTM and YTC. how do you discount the coupon rate?
you discount using the yield rate
Feb
20
comment Bad notation in Fulton's algebraic curves book
Seems to me like this is defined on Page 3 (it's the derivative). It's also listed in the "Notation"/Table of Symbols on page 117.
Feb
12
comment House loses value each year. How long will it take for the house to be worth $150000
that looks right to me... can you solve it from there?
Feb
12
comment House loses value each year. How long will it take for the house to be worth $150000
Have you tried setting up an equation to solve? Do you know about logarithms?
Feb
12
revised House loses value each year. How long will it take for the house to be worth $150000
added 10 characters in body; edited tags
Feb
8
revised If a and b are in G and ab=ba, then we say a and b commute. Assuming a and b commute, prove:
added assumptions to body
Feb
8
comment If a and b are in G and ab=ba, then we say a and b commute. Assuming a and b commute, prove:
your steps aren't right, you can't go from $xabx^{-1}$ to $xax^{-1}b$ (you do moves like this a couple times). all you know is that $a$ and $b$ commute, you know nothing about whether $x$ commutes with $a$ or $b$. additionally, you claim this is by the associative property, which it is not (it's commutative).
Feb
8
comment What integration rule to use?
Use partial fraction decomposition.