a) `(x-1)^(x+2)=(x-1)^(x+6)`
`<=> x+2=x+6`
`<=> 0x = 4 (VN)`
b) `(1+2y)/18 = (1+4y)/24 = (1+6y)/(6x)`
Có : `(1+2y)/18 = (1+4y)/24`
`<=> 24(1+2y) = 18(1+4y)`
`<=> 4(1+2y) = 3(1+4y)`
`<=> 4 + 8y = 3+12y`
`<=> 4y = 1`
`<=> y=1/4`
`=> (1+6. 1/4)/(6x) = (1+2. 1/4)/18`
`<=> 5/2 : 6x = 1/12`
`<=> 6x= 5/2 : 1/12`
`<=> x = 30`