Bài 1. Thực hiện phép tính ( tính nhanh nếu có thể ):
a) \(\dfrac{9}{4}\) + \(\dfrac{-7}{6}\).\(\dfrac{3}{7}\)
b) \(\dfrac{1}{2024}\) . \(\dfrac{-3}{8}\) - \(\dfrac{13}{8}\) . \(\dfrac{1}{2024}\) + \(\dfrac{1}{2024}\)
c) 9.\(\left(\dfrac{1}{3}\right)^3\): [ \(\left(\dfrac{-2}{3}\right)^2\)+ 0,5 - \(1\dfrac{1}{2}\) ] + 9990
d) \(\dfrac{-7}{11}\) + ( 31,75 - \(\dfrac{4}{11}\) ) - ( -68,25 )
`a, 9/4 + (-7)/6 . 3/7`
`= 9/4 - 1/2`
`=9/4 - 2/4`
`= 7/4`
`b, 1/2024 . (-3)/8 - 13/8 . 1/2024 + 1/2024`
`= 1/2024 . (-3/8 - 13/8 + 1)`
`= 1/2024 .(-2 + 1)`
`= 1/2024 . (-1)`
`= -1/2024`
\(a,\dfrac{9}{4}+\dfrac{-7}{6}.\dfrac{3}{7}\)
\(=\dfrac{9}{4}-\dfrac{1}{2}\)
\(=\dfrac{9}{4}-\dfrac{2}{4}\)
\(=\dfrac{7}{4}\)
\(b,\dfrac{1}{2024}.\dfrac{-3}{8}-\dfrac{13}{8}.\dfrac{1}{2024}+\dfrac{1}{2024}\)
\(=\dfrac{1}{2024}.\left(\dfrac{-3}{8}-\dfrac{13}{8}+1\right)\)
\(=\dfrac{1}{2024}.\left(\dfrac{-16}{8}+1\right)\)
\(=\dfrac{1}{2024}.\left(-2+1\right)\)
\(=\dfrac{1}{2024}.\left(-1\right)\)
\(=\dfrac{-1}{2024}\)
`c, 9. (1/3)^3 :[((-2)/3)^2 + 0,5 - 1 1/2]+ 999^0`
`= 9 . 1/27 : (4/9 + 0,5 - 1,5)+ 1`
`= 1/3 : (4/9 - 1) + 1`
`= 1/3 : (-5/9) + 1`
`= -3/5 + 1`
`= 2/5`
`d, (-7)/11 + (31,75 - 4/11) - (-68,25)`
`= -7/11 + 31,75 - 4/11 + 68,25`
`= (31,75 + 68,25) + (-7/11 - 4/11)`
`= 100 - 1`
`= 99`