simple exponential equation help!

solve (without using logs)

3(^2x+1)=70

Question

simple exponential equation help!

solve (without using logs)

3(^2x+1)=70

dumbcow · Answer

i get x = 1.43 but i used logs so it doesnt count

dumbcow · Answer

why cant you use logs

anonymous · Answer

how do you do it with logs then?

anonymous · Answer

haha
i was already excited what the solution is xD

anonymous · Answer

well it's grade 11 functions and apps, and logs is apparently advanced functions so she doesnt want us using them. but whatever, i'll use logs.

dumbcow · Answer

take log base 3 of both sides
->2x+1 = log3(70)
get x by itself
_>2x = log3(70) -1
->x = (1/2)*(log3(70)-1)
use change of base formula to find log3(70)

dumbcow · Answer

log3(70) = log(70)/log(3)
sorry you prob didnt know what i meant

dumbcow · Answer

wait sorry i think i know what your teacher wanted
3^2x+1 = 3^2x*3^1 = 70
divide 3 on both sides
3^2x = 70/3
square root both sides
3^x = sqrt(70/3) = 4.83
then estimate your best guess for x