Question

Tìm x,y nguyên dương biết:

a)2^x+1.3^y=12^x

b)2^x+2^y=2^x+y

c)2^x-2^y=256

d)5^x+y²=1/4

e)2x²-16x+y²=-22

f)7x+4y=23

h)x²-xy=6x-5y-8

giải câu nào hay câu ấy nhé ^.^

Answer 1

a) \(2^{x+1}.3^y=12^x=4^x.3^x=2^{2x}.3^x\)

\(\Rightarrow\left\{{}\begin{matrix}x+1=2x\\y=x\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=1\\y=1\end{matrix}\right.\)

Answer 2

\(c,2^x-2^y=2y\left(2^{x-y}-1\right)=256\)(vì x > y)

Ta có; \(256⋮\left(2^{x-y}-1\right)\Rightarrow2^{x-y}-1=1\)

\(\Rightarrow x-y=1\)

\(\Rightarrow2^y=2^8\Rightarrow y=8\)

vậy x = 9; y=8

\(\)

Answer 3

bn ni đăng hỏi hết ~~