1.Thực hiện phép tính bằng cách hợp lí
a)−49+(\(-\dfrac{5}{6}\))−\(\dfrac{17}{4}\) b\(5\dfrac{1}{2}+\left(-3\right)\) c)\(4\dfrac{9}{11}\)+(−\(2\dfrac{1}{11}\))
2.tính
a)4,3 - (1,2) b) 0 - (-0,4) c) \(-\dfrac{2}{3}-\dfrac{-1}{3}\) d) \(-\dfrac{1}{2}-\dfrac{-1}{6}\)
Mong mọi người giải dùm mình nha , mình cần gấp lắm
1.
a)\(-49+\left(-\dfrac{5}{6}\right)-\dfrac{17}{4}\)
\(=-49-\dfrac{5}{6}-\dfrac{17}{4}\)
\(=\dfrac{-588}{12}-\dfrac{10}{12}-\dfrac{51}{12}\)
\(=\dfrac{-588-10-51}{12}\)
\(=-\dfrac{649}{12}\)
b) \(5\dfrac{1}{2}+\left(-3\right)\)
\(=\dfrac{11}{2}-3\)
\(=\dfrac{11}{2}-\dfrac{6}{2}\)
\(=\dfrac{11-6}{2}\)
\(=\dfrac{5}{2}\)
c) \(4\dfrac{9}{11}+\left(2-2\dfrac{1}{11}\right)\)
\(=\dfrac{53}{11}+2-\dfrac{23}{11}\)
\(=\dfrac{53-23}{11}+2\)
\(=\dfrac{30}{11}+2\)
\(=\dfrac{30}{11}+\dfrac{22}{11}\)
\(=\dfrac{30+22}{11}\)
\(=\dfrac{52}{11}\)
2.
a) \(4,3-1,2=3,1\)
b) \(0-\left(-0,4\right)=0+0,4=0,4\)
c) \(-\dfrac{2}{3}-\dfrac{-1}{3}=-\dfrac{2}{3}+\dfrac{1}{3}=-\dfrac{1}{3}\)
d) \(-\dfrac{1}{2}-\dfrac{-1}{6}=-\dfrac{1}{2}+\dfrac{1}{6}=-\dfrac{3}{6}+\dfrac{1}{6}=-\dfrac{2}{6}=-\dfrac{1}{3}\)
