125%.(−12)2(−12)2:(1516−1,5)+20080(1516−1,5)+20080
=1.25x0,25:(1,3125-1,5)+1
=0,3125:(-0,1875)+1
=-5/3+1
=-2/3
vậy.......
23.5+25.7+27.9+29.11+211.13+213.15=23.5+25.3+27.9+29.11+211.13+213.15
\(=\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{9}+\dfrac{1}{9}-\dfrac{1}{11}+\dfrac{1}{11}-\dfrac{1}{13}+\dfrac{1}{13}-\dfrac{1}{15}\)
\(=\dfrac{1}{3}-\dfrac{1}{15}=\dfrac{4}{15}\)
câu này viết sai đề nhé!!!!
Bài 2. Tìm x, biết
x:3115=11123115=111
\(\Rightarrow x=1\dfrac{1}{12}\cdot3\dfrac{1}{15}=\dfrac{299}{90}\)
vậy
34.x=27
\(\Rightarrow x=27:\dfrac{3}{4}=36\)34.x=27
vậy.....
x.14=58.23x
\(\Rightarrow x=\dfrac{5}{8}\cdot\dfrac{2}{3}:\dfrac{1}{4}=\dfrac{5}{3}\)
vậy.........14=58.23
(x+14):37=16
\(x:\dfrac{3}{7}+\dfrac{1}{4}:\dfrac{3}{7}=\dfrac{1}{6}\)
\(x:\dfrac{3}{7}=\dfrac{1}{6}-\dfrac{1}{4}:\dfrac{3}{7}\)
\(x:\dfrac{3}{7}=-\dfrac{5}{12}\)
\(x=-\dfrac{5}{12}\cdot\dfrac{3}{7}=-\dfrac{5}{28}\)
vậy............
34−2.|2x−23|=2
\(\dfrac{3}{4}-4\left|x-\dfrac{1}{3}\right|=2\)
\(4\left|x-\dfrac{1}{3}\right|=\dfrac{3}{4}-2\)
\(4\left|x-\dfrac{1}{3}\right|=-1,25\)
\(\left|x-\dfrac{1}{3}\right|=-1,25:4=-0,3125\)(loại)
vậy.............
2 3x−12x=52
\(\dfrac{2}{3}-\left(1+\dfrac{1}{2}\right)x=\dfrac{5}{2}\)
\(\dfrac{2}{3}-1,5x=\dfrac{5}{2}\)
\(x=\left(\dfrac{2}{3}-\dfrac{5}{2}\right):1,5=-\dfrac{11}{9}\)
vậy......