Question

if 5^x + 4^y = 3189 and 5^(x-3) + 4^(y+1) =281 then x-y= ?

Answer 1

take natural log of both sides!

for the second one, simplify it a bit before taking log.

Answer 2

x-y=2

Answer 3

@lgbasallote

Answer 4

@Yahoo! , @apoorvk is correct, its a bit like that last question i helped you with

Answer 5

try to find the value of 5^x and 4^y first ... not sure though..

Answer 6

the answer is 2

Answer 7

let 5^x = a and 4^y=b

Answer 8

ok

Answer 9

though there might be some other better method ..

Answer 10

No @experimentX plz continue let see wat u get plz

Answer 11

a + b = 3189
a/125 + 4 = 281

Answer 12

i am wondering what the snap way to do this is
i get
\[a+b=3189, \frac{1}{125}a+4b=281\]

Answer 13

but since you are looking only for \(x-y\) maybe there is an easier way

Answer 14

i got b=64 a=3125

Answer 15

but i think this does not help

Answer 16

it helps a lot

Answer 17

ok so \(4^y=64\implies y=3\) right?

Answer 18

still there must be some algebraic trick ... if somebody gets it .. let me know first

Answer 19

similarly \(5^x=3125\implies ...\)

Answer 20

maybe this is the best way. i cannot think of a snap one
notice it does not use logs

Answer 21

6

Answer 22

5^5= 3125

Answer 23

actually \(5^5=3125\) and \(5-3=2\)

Answer 24

sorry

Answer 25

thxxxx @phi @satellite73 @experimentX

Answer 26

yw