giúp mình 2 bài toán nâng cao này với:
1,thực hiện phép tính bằng cách hợp lí
a,\(\dfrac{11}{125}\)-\(\dfrac{17}{18}\)-\(\dfrac{5}{7}\)+\(\dfrac{4}{9}\)+\(\dfrac{17}{14}\)
b,1-\(\dfrac{1}{2}\)+2-\(\dfrac{2}{3}\)+3-\(\dfrac{3}{4}\)+4-\(\dfrac{1}{4}\)-3-\(\dfrac{1}{3}\)-2-\(\dfrac{1}{2}\)-1
2,tìm x biết
a,2x+\(\dfrac{1}{2}\)=\(\dfrac{-5}{3}\)
b,\(\dfrac{1}{7}\)-\(\dfrac{3}{5}\)x=\(\dfrac{3}{5}\)
c,\(\dfrac{3}{4}\)x+\(\dfrac{1}{2}\)=\(\dfrac{-3}{5}\)
d,\(\dfrac{-2}{15}\)-x=\(\dfrac{-3}{10}\)
giúp với mình cần gấp giúp với !!!!!!!!!!!!!!!!!!!
\(.2.\)
\(a.\)
\(2x+\dfrac{1}{2}=-\dfrac{5}{3}\)
\(\Rightarrow2x=-\dfrac{5}{3}-\dfrac{1}{2}=-\dfrac{13}{6}\)
\(\Rightarrow x=-\dfrac{13}{6}:2=-\dfrac{13}{12}\)
Vậy : \(x=-\dfrac{13}{12}\)
\(b.\)
\(\dfrac{1}{7}-\dfrac{3}{5}x=\dfrac{3}{5}\)
\(\Rightarrow\dfrac{3}{5}x=\dfrac{1}{7}-\dfrac{3}{5}=-\dfrac{16}{35}\)
\(\Rightarrow x=-\dfrac{16}{35}:\dfrac{3}{5}=-\dfrac{16}{21}\)
Vậy : \(x=-\dfrac{16}{21}\)
\(c.\)
\(\dfrac{3}{4}x+\dfrac{1}{2}=-\dfrac{3}{5}\)
\(\Rightarrow\dfrac{3}{4}x=-\dfrac{3}{5}-\dfrac{1}{2}=-\dfrac{11}{10}\)
\(\Rightarrow x=-\dfrac{11}{10}:\dfrac{3}{4}=-\dfrac{22}{15}\)
Vậy : \(x=-\dfrac{22}{15}\)
\(d.\)
\(-\dfrac{2}{15}-x=-\dfrac{3}{10}\)
\(\Rightarrow x=-\dfrac{2}{15}-\left(-\dfrac{3}{10}\right)=\dfrac{1}{6}\)
Vậy : \(x=\dfrac{1}{6}\)
A= \(\dfrac{11}{125}\) + \(\left(\dfrac{4}{9}-\dfrac{17}{18}\right)+\left(\dfrac{17}{14}-\dfrac{5}{7}\right)\)
A=\(\dfrac{11}{125}+\left(\dfrac{8}{18}-\dfrac{17}{18}\right)+\left(\dfrac{17}{14}-\dfrac{10}{14}\right)\)
A=\(\dfrac{11}{125}-\dfrac{9}{18}+\dfrac{7}{14}\)
A=\(\dfrac{11}{125}+\left(-\dfrac{1}{2}+\dfrac{1}{2}\right)\)\(\)
A= \(\dfrac{11}{125}\)
VẬY: A= \(\dfrac{11}{125}\)
