यदि `3^(x+y)=81` और `81^(x-y)=3` है तो `x` का मान ज्ञात करें।

Options

A. `42`
B. `15/8`
C. `17/8`
D. `39`

Answer

C

Explanation

`3^(x+y)=81`
`3^(x+y)=3^(4)`
`impliesx+y=4`
`81^(x-y)=3` ………..i
`3^(4x-46)=3^(1)`
`implies4x-4y=1`……………ii
from equation i and ii
`4x-4y=1`
`4x+4y=16`
`=8x=17`
`x=17/8`