Rút gọn phân số : a, -14.11+14.12/11.21-7.22 ; b, 2.8^4.27^2/2^7.6^7 ; c, 2^12.3^5-4^6.9^2/(2^2.3)^6+8^4.3^5

Đáp án:

`a, (-14.11+14.12)/(11.21-7.22)`

`= (-154+168)/(231-154)`

`= 14/77`

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`b, (2.8^4 .27^2)/(2^7 .6^7)`

`= (2.(2^3)^4 .(3^3)^2)/(2^7 .2^7 .3^7)`

`= (2.2^12 .3^6)/(2^14 .3^7)`

`= (2^13 .3^6)/(2^14 .3^7)`

`= 1.1/2.3`

`=1/6`

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`c,  (2^12. 3^5-4^6. 9^2)/((2^2 .3)^6+8^4 .3^5)`

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

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

`= (3^5-3^4)/(3^6+3^5)`

`= (3^4.(3-1))/(3^5.(3+1))`

`= ((3-1))/(3.(3+1))`

`= (2)/(3.4)`

`= 1/6`