`\color{#274e13}{♡}\color{#38761d}{C}\color{#55953a}{h}\color{#79b95d}{a}\color{#98d97c}{n}\color{#b7fa99}{h}`

`bb(Bài 7.)`

`hat(xOy) + hat(yOz) + hat(zOx) = 360^o`

`to 120^o + 110^o + hat(zOx) = 360^o`

`to 230^o + hat(zOx) = 360^o`

`to hat(zOx) = 360^o - 230^o`

`to hat(zOx) = 130^o`

`bb(Bài 8.)`

`bb(a.)`

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

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

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

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

`A = (2^12 . 3^4 . 2)/(2^8 . 3^4 . (1 + 16 . 3))`

`A = (2^13 . 3^4)/(2^8 . 3^4 . 49)`

`A = 2^5 / 49 = 32/49`

`bb(b.)`

`M = (3/2 + 1 - 3/4)/(5/2 + 5/3 - 1.25) - (3/8 - 0.3 + 3/11 + 3/14)/(0.625 - 0.5 + 5/11 + 5/14)`

`M = (3 . (1/2 + 1/3 - 1/4))/(5 . (1/2 + 1/3 - 1/4)) - (3 . (1/8 - 1/10 + 1/11 + 1/14))/(5 . (1/8 - 1/10 + 1/11 + 1/14))`

`M = 3/5 - 3/5`

`M = 0`