SOlve for x

johntuan · #1 $Old$ October 25th, 2007, 11:01 PM

0.1=25.6(1+.4x)^-4/3

If someone can help me with steps provided it would be appreciated.

Jhevon · #2 $Old$ October 25th, 2007, 11:19 PM

Quote:

Originally Posted by johntuan $View Post$

0.1=25.6(1+.4x)^-4/3

If someone can help me with steps provided it would be appreciated.

$0.1 = 25.6(1 + 0.4x)^{-4/3}$ ...........divide both sides by 25.6

$\Rightarrow \frac {0.1}{25.6} = (1 + 0.4x)^{-4/3}$ .........raise both sides to the -3/4th power

$\Rightarrow \left( \frac {0.1}{25.6} \right)^{-3/4} = 1 + 0.4x$ .........subtract 1 from both sides

$\Rightarrow \left( \frac {0.1}{25.6} \right)^{-3/4} - 1 = 0.4x$ ..........divide both sides by 0.4

$\Rightarrow \frac { \left( \frac {0.1}{25.6} \right)^{-3/4} - 1 }{0.4} = x$ ...............now punch into your calculator and simplify

ticbol · #3 $Old$ October 25th, 2007, 11:27 PM

0.1=25.6(1+.4x)^-4/3

If that is
0.1 = 25.6(1 +0.4x)^(-4/3),
then,

The idea is to separate the x alone by itself only.

Divide both sides by 25.6
0.1/25.6 = (1 +0.4x)^(-4/3)

Raise both sides top their (-3/4) powers,
(0.1 /25.6)^(-3/4) = 1 +0.4x
0.4x = (0.1 /25.6)^(-3/4) -1

Divide both sides by 0.4,
x = [(0.1 /25.6)^(-3/4) -1] /(0.4)
x = 157.5 --------------------------answer.

johntuan · #4 $Old$ October 25th, 2007, 11:51 PM

Quote:

Originally Posted by Jhevon $View Post$

$0.1 = 25.6(1 + 0.4x)^{-4/3}$ ...........divide both sides by 25.6

$\Rightarrow \frac {0.1}{25.6} = (1 + 0.4x)^{-4/3}$ .........raise both sides to the -3/4th power

$\Rightarrow \left( \frac {0.1}{25.6} \right)^{-3/4} = 1 + 0.4x$ .........subtract 1 from both sides

$\Rightarrow \left( \frac {0.1}{25.6} \right)^{-3/4} - 1 = 0.4x$ ..........divide both sides by 0.4

$\Rightarrow \frac { \left( \frac {0.1}{25.6} \right)^{-3/4} - 1 }{0.4} = x$ ...............now punch into your calculator and simplify

ok I have a question to cancel out the ^(-4/3) for any function we would raise both sides to (-3/4)? Just the opposite?

Jhevon · #5 $Old$ October 26th, 2007, 12:11 AM

Quote:

Originally Posted by johntuan $View Post$

ok I have a question to cancel out the ^(-4/3) for any function we would raise both sides to (-3/4)? Just the opposite?

yes, because (-4/3)*(-3/4) = 1 and we wanted the power on the right to be 1 so we could simplify