Đáp án+Giải thích các bước giải:

`a)A=(2^12 . 3^5-4^6 . 9^2)/((2^2 .3)^6 +8^4 . 3^5)-(5^10 . 7^3 -25^5 . 49^2)/((125.7)^3 +5^9 . 14^3)`

`A=(2^12 . 3^5 -2^12 . 3^4)/(2^12 . 3^6 +2^12 .3^5)-(5^10 . 7^3 - 5^10 . 7^4)/(5^9 .7^3 +5^9 .7^3 . 2^3)`

`A=(2^12 . 3^4 (3-1))/(2^12 . 3^5 (3+1))-(5^10 . 7^3 (1-7))/(5^9 .7^3 (1+8))`

`A=(2^13 . 3^4)/(2^14 . 3^5)-(5^10 .7^3 .(-6))/(5^9 .7^3 . 3^2)`

`A=1/(2.3)-(5.(-6))/(3^2)`

`A=1/6-(-30)/9`

`A=1/6+10/3=1/6+20/6=21/6=7/2.`