~Gửi bạn~
`c)(1/64)^x =(-1/8)^14`
`=>[(-1/8)^2]^x= (-1/8)^14`
`=>(-1/8)^(x.2)=(-1/8)^14`
`=>2x=14=>x=7`
`b)(4/9)^(x+1)=(8/27)^6`
`=>(4/9)^(x+1)=[(2/3)^3]^6`
`=>(4/9)^(x+1)=(2/3)^18`
`=>[(2/3)^2]^(x+1)=(2/3)^18`
`=>(2/3)^(2(x+1))=(2/3)^18`
`=>2(x+1)=18`
`=>x+1=9=>x=8`