# Equation and inverse function problems

• Aug 5th 2011, 07:11 PM
kiimberly2
Equation and inverse function problems
solve for:

9^x -5 x 3^x +6= 0

i've been trying to solve for this in which i have let U equal 3x and then by using the null factor law work out the answer. but somehow i didn't get the right answer :L

and also for:

Find the inverse function of

y=loge (x + 1) -2

in which i did

x= loge (y +1 ) -2

then x -2 = loge ( y+1)

but i seemed to get the wrong answer.

any help would be greatly appreciated!!
• Aug 5th 2011, 07:29 PM
abhishekkgp
Re: need help with math questions
Quote:

Originally Posted by kiimberly2
solve for:

9^x -5 x 3^x +6= 0

i've been trying to solve for this in which i have let U equal 3x and then by using the null factor law work out the answer. but somehow i didn't get the right answer :L

and also for:

Find the inverse function of

y=loge (x + 1) -2

in which i did

x= loge (y +1 ) -2

then x -2 = loge ( y+1)

but i seemed to get the wrong answer.

any help would be greatly appreciated!!

for the first one take \$\displaystyle 3^x=y\$. Then \$\displaystyle 9^x=y^2\$. Your problem boils down to solving a quadratic.
• Aug 5th 2011, 07:40 PM
Prove It
Re: need help with math questions
Quote:

Find the inverse function of

y=loge (x + 1) -2

in which i did

x= loge (y +1 ) -2

then x +2 = loge ( y+1)

but i seemed to get the wrong answer.

any help would be greatly appreciated!!
You're almost there after making the change shown in the quote. Solve this equation for y.
• Aug 6th 2011, 11:45 AM
Siron
Re: need help with math questions
Notice the logarithmic function is the inverse function of the exponential function.