Đáp án:
`a) (2/3)^x=(4/9)^4`
`<=> (2/3)^x=((2/3)^2)^4`
`<=> (2/3)^x=(2/3)^8`
`<=> x=8`
`b) (x+1)/12=-3/4`
`<=> (x+1)/12=(-3.3)/(4.3)`
`<=> (x+1)/12=-9/12`
`<=> x+1=-9`
`<=> x=-10`
`c) (1/2)^(x+1)=1/32`
`<=> (1/2)^(x+1)=(1/2)^5`
`<=> x+1=5`
`<=> x=4`
`d) (2/3)^(x-2)=(4/9)^4`
`<=> (2/3)^(x-2)=(2/3)^8`
`<=> x-2=8`
`<=> x=10`