Math Is Fun Forum

pman

Member

Registered: 2005-11-03

Posts: 10

need explaination

hi can someone explain in detail how to solve this kind of problem please:

 1)  7*4^x = 5*9^x

2)log3 3 + log9 1

you should use logarithms to solve it, thx!

Jai Ganesh

Administrator

Registered: 2005-06-28

Posts: 46,182

Re: need explaination

1) xlog4 + log7 = xlog9+ log5
xlog4 - xlog9 = log5 - log7
xlog9 - xlog4 = log7 - log5
x(log9 - log4) = log7 - log5
x = (log7 - log5)/(log9 - log4)

The second question isn't clear

---

It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

ryos

Member

Registered: 2005-08-04

Posts: 394

Re: need explaination

I think that, on the second question, he means "log base 3 of 3 + log base 9 of 1".

If so, it's easy. 3¹ = 3, and 9^0 = 1. So, 1 + 0 = 1.

---

El que pega primero pega dos veces.

pman

Member

Registered: 2005-11-03

Posts: 10

Re: need explaination

thx alot guys