a: \(-\dfrac{3}{4}-\dfrac{7}{6}=-\dfrac{9}{12}-\dfrac{14}{12}=-\dfrac{23}{12}\)
b: \(1,275-4,27=-2,995\)
c: \(-0,25+1,8\left(1,5-\dfrac{9}{2}\right)^2\)
\(=-\dfrac{1}{4}+\dfrac{9}{5}\left(\dfrac{3}{2}-\dfrac{9}{2}\right)^2\)
\(=-\dfrac{1}{4}+\dfrac{9}{5}\cdot3^2=-\dfrac{1}{4}+\dfrac{81}{5}=\dfrac{-5+324}{20}=\dfrac{319}{20}\)
d: \(\dfrac{5}{7}-\left(0,2-\dfrac{2}{7}\right)=\dfrac{5}{7}-0,2+\dfrac{2}{7}=\dfrac{7}{7}-0,2=1-0,2=0,8\)
e: \(\left(-\dfrac{5}{6}\right)-\left(-1,8\right)+\left(-\dfrac{1}{6}\right)-0,8\)
\(=-\dfrac{5}{6}+1,8-\dfrac{1}{6}-0,8\)
=-1+1=0
f: \(125-\left(6,5+\dfrac{9}{17}\right)-\left(\dfrac{25}{17}-\dfrac{7}{2}\right)\)
\(=125-6,5-\dfrac{9}{17}-\dfrac{25}{17}+\dfrac{7}{2}\)
\(=125-6,5+3,5-\dfrac{34}{17}\)
=125-3-2
=120
`a, -3/4 - 7/6`
` = -9/12 - 14/12`
` = -23/12`
`b, 1,275 - 4,27`
` = 1,275 + (-4,27)`
` = -2,995`
`c, -0,25 + 1, 8 * (1,5 - 9/2)^2`
` = -1/4 + 9/5 * (3/2 - 9/2) ^2`
` = -1/4 + 9/5 * (-3)^2`
` = -1/4 + 9/5 * 9`
` = -1/4 + 81/5`
` = 319/20`
`d, 5/7 - (0,2 -2/7)`
` = 5/7 - 1/5 + 2/7`
` = (5/7 + 2/7) - 1/5`
` = 1 - 1/5`
`= 4/5`
