câu 1 Thực hiệm phép tính
a) _ $\frac{2}{5}$ + $\frac{-1}{3}$ – 75$^{o}$/$_{o}$
b) $\frac{-23}{127}$ . $\frac{127}{69}$ – $\frac{5}{12}$ – 1 $\frac{1}{9}$
c) 25$\frac{1}{3}$ . $\frac{-18}{19}$ – 28$\frac{1}{3}$ . $\frac{-18}{19}$
câu 1 Thực hiệm phép tính
a) _ $\frac{2}{5}$ + $\frac{-1}{3}$ – 75$^{o}$/$_{o}$
b) $\frac{-23}{127}$ . $\frac{127}{69}$ – $\frac{5}{12}$ – 1 $\frac{1}{9}$
c) 25$\frac{1}{3}$ . $\frac{-18}{19}$ – 28$\frac{1}{3}$ . $\frac{-18}{19}$
Đáp án + giải thích bước giải :
`a) (-2)/5 + (-1)/3 – 75%`
`= (-11)/15 – 75%`
`= (-89)/60`
`b) (-23)/127 . 127/69 – 5/22 – 1 1/9`
`= (-1)/3 – 5/12 – 10/9`
`= (-3)/4 – 10/9`
`= (-67)/36`
`c) 25 1/3 . (-18)/19 – 28 1/3 . (-18)/19`
`= (-18)/19 . (25 1/3 – 28 1/3)`
`= (-18)/19 . (-3)`
`= 54/19`
Đáp án:
`a)`
`2/(-5) + (-1)/3 – 75%`
`= ((-6)+(-5))/15 – 3/4`
`= -11/15 – 3/4 `
`= (-44-45)/60 = -89/60`
`b)`
`(-23)/127 . 127/69 – 5/12 – 1 1/9`
`= -1/3 – 5/12 – 10/9`
`= (-12-15-40)/36 `
`= -67/36`
`c) 25 1/3 . (-18)/19 – 28 1/3 . (-18)/19`
`= (-18)/19 . ( 25 1/3 – 28 1/3 )`
`= (-18)/19 . ( 25 + 1/3 – 28 – 1/3 )`
`= (-18)/19 . (-3) = 54/19`