bài 1: tính
a) \(\dfrac{3}{4}\)+(\(\dfrac{1}{2}\)-\(\dfrac{3}{4}\))
b) \(\dfrac{5}{12}\).\(\dfrac{16}{13}\)-\(\dfrac{5}{12}\).\(\dfrac{3}{13}\)
c) \(\dfrac{-1}{2}\)+(\(\dfrac{1}{3}\)+\(\dfrac{5}{18}\)).40%
bài 2: tìm x biết
a)...
Đọc tiếp
bài 1: tính
a) \(\dfrac{3}{4}\)+(\(\dfrac{1}{2}\)-\(\dfrac{3}{4}\))
b) \(\dfrac{5}{12}\).\(\dfrac{16}{13}\)-\(\dfrac{5}{12}\).\(\dfrac{3}{13}\)
c) \(\dfrac{-1}{2}\)+(\(\dfrac{1}{3}\)+\(\dfrac{5}{18}\)).40%
bài 2: tìm x biết
a) x+1,5=-6,3
b)\(\dfrac{5}{6}\).x-\(\dfrac{1}{3}\)=\(\dfrac{4}{7}\)
c)\(\dfrac{x}{2}\)=\(\dfrac{8}{x}\)
Bài 2:
a: x+1,5=-6,3
=>x=-6,3-1,5
=>x=-7,8
b: \(\dfrac{5}{6}x-\dfrac{1}{3}=\dfrac{4}{7}\)
=>\(\dfrac{5}{6}x=\dfrac{4}{7}+\dfrac{1}{3}=\dfrac{19}{21}\)
=>\(x=\dfrac{19}{21}:\dfrac{5}{6}=\dfrac{19}{21}\cdot\dfrac{6}{5}=\dfrac{19\cdot2}{7\cdot5}=\dfrac{38}{35}\)
c: ĐKXĐ: x<>0
\(\dfrac{x}{2}=\dfrac{8}{x}\)
=>\(x^2=16\)
=>\(\left[{}\begin{matrix}x=4\left(nhận\right)\\x=-4\left(nhận\right)\end{matrix}\right.\)
bài 1:
a: \(\dfrac{3}{4}+\left(\dfrac{1}{2}-\dfrac{3}{4}\right)=\dfrac{3}{4}+\dfrac{1}{2}-\dfrac{3}{4}=\dfrac{1}{2}\)
b: \(\dfrac{5}{12}\cdot\dfrac{16}{13}-\dfrac{5}{12}\cdot\dfrac{3}{13}\)
\(=\dfrac{5}{12}\left(\dfrac{16}{13}-\dfrac{3}{13}\right)\)
\(=\dfrac{5}{12}\cdot\dfrac{13}{13}=\dfrac{5}{12}\)
c: \(-\dfrac{1}{2}+\left(\dfrac{1}{3}+\dfrac{5}{18}\right)\cdot40\%\)
\(=\dfrac{-1}{2}+\dfrac{6+5}{18}\cdot\dfrac{2}{5}\)
\(=\dfrac{-1}{2}+\dfrac{11}{9}\cdot\dfrac{1}{5}=\dfrac{-1}{2}+\dfrac{11}{45}=\dfrac{-45+22}{90}=\dfrac{-23}{90}\)