helpppppppppppppppppppppppp

`a)` `M=(2^12 .3^5 -4^6 .81)/((2^2 .3)^6 +8^4 .3^5)`

`M=(2^12 .3^5 -(2^2)^6 .3^4)/(2^2 . 2^6 .3^6 +(2^3)^4 .3^5)`

`M=(2^12 .3^5 -2^12 .3^4)/(2^12 .3^6 +2^12 .3^5)`

`M=(2^12 .3^4 .(3-1))/(2^12 .3^4 .(3^2 +3))`

`M=(2)/12`

`M=1/6`

Vậy `M=1/6`

`b)` `N=(2.8^4 .27^2 +4.6^9)/(2^7 .6^7 +2^7 .40.9^4)`

`N=(2.(2^3)^4 .(3^3)^2 +2^2 .2^9 .3^9)/(2^7 .2^7 .3^7 +2^7 .2^3 .5.(3^2)^4)`

`N=(2.2^12 .3^6 +2^11 .3^9)/(2^14 .3^7 +2^10 .5.3^8)`

`N=(2^11 . 3^6 . (2^2 +3^3))/(2^10 .3^7 .(3^4 +5.3))`

`N=(2^11 .3^6 .31)/(2^10 .3^7 .31)`

`N=2/3`

Vậy `N=2/3`