Math Is Fun Forum

pashula

Member

Registered: 2009-06-22

Posts: 2

logarithms

what is log 9 base 18 + log 2401 base 7 - log (x-6) base 2

Last edited by pashula (2009-06-22 06:21:40)

pashula

Member

Registered: 2009-06-22

Posts: 2

Re: logarithms

Brandon bought a government savings bond for $1,100. He was told that when the bond can be cashed in 5 years that he would get $1,444.48. If the interest on the bond is compounded annually, what is the interest rate on the bond?

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: logarithms

1100 is multiplied by some number five times, and 1444.48 is the result.

ie. 1444.48 = 1100*k^5.

Rearranging, k = [sup]5[/sup]√(1444.48/1100), which is ~1.056.
The interest rate is therefore 5.6%.

---

Why did the vector cross the road?
It wanted to be normal.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: logarithms

Hi pashula;

  The only one of those 3 terms that can be simplified is:

Last edited by bobbym (2009-06-22 09:19:07)

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: logarithms

You can't express the first term without using logs in some way, but you might find one of these a simpler expression:

---

Why did the vector cross the road?
It wanted to be normal.