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đề chính xác là
a/ \(13-2\times\left(36-5\times x\right)=1\)
b/ \(53-10\times\left(40-7\times x\right)=3\)
c/ \(\frac{3}{4}-\frac{1}{6}\div x=0,375\)
\(x+\frac{15}{7}=\frac{9}{2}\)
\(x=\frac{9}{2}-\frac{15}{7}=\frac{33}{14}\)
\(x-\frac{3}{4}=\frac{7}{2}\)
\(x=\frac{7}{2}+\frac{3}{4}=\frac{17}{4}\)
\(x.\frac{7}{8}=\frac{12}{5}\)
\(x=\frac{12}{5}:\frac{7}{8}=\frac{96}{35}\)
\(\frac{5}{6}:x=\frac{4}{3}\)
\(x=\frac{5}{6}:\frac{4}{3}=\frac{5}{8}\)
- a) x=9/2-15/7=33/14
- b) x=7/2+3/4=17/4
- c) x=12/5:7/8=61/35
- d) x=5/6:4/3=5/8
- k nha
\(\frac{5}{1.6}\)+ \(\frac{5}{6.11}\)+ .........+\(\frac{5}{501.506}\)
=\(\frac{1}{1.6}+\frac{1}{6.11}+.....+\frac{1}{501.506}\)
=\(\frac{1}{1}-\frac{1}{6}+\frac{1}{6}-\frac{1}{11}+......+\frac{1}{501}-\frac{1}{506}\)
=\(\frac{1}{1}-\frac{1}{506}\)
= tự tính nha
a) \(1\frac{5}{7}\)x \(\frac{3}{4}\)= \(\frac{12}{7}\)x \(\frac{3}{4}\)= \(\frac{9}{7}\)
b) \(\frac{10}{11}\)x \(1\frac{1}{3}\)= \(\frac{10}{11}\)x \(\frac{4}{3}\)= \(\frac{40}{33}\)
c) 3,57 x 4,1 + 2,43 x 4,1
= 4,1 x ( 3,57 + 2,43 )
= 4,1 x 6
= 24,6
d) 3,42 : 0,57 x 8,4 - 6,8
= 6 x 8,4 - 6,8
= 50,4 - 6,8
= 43,6
2/
a) \(\frac{4}{1\cdot5}+\frac{4}{5\cdot9}+\frac{4}{9\cdot13}+\frac{4}{13\cdot17}+\frac{4}{17\cdot21}\)
\(=\left(1-\frac{1}{5}+\frac{1}{5}-\frac{1}{9}+....+\frac{1}{17}-\frac{1}{21}\right)\)
\(=1-\frac{1}{21}=\frac{20}{21}\)
b) \(\left(1-\frac{1}{2}\right)\cdot\left(1-\frac{1}{3}\right)\cdot\left(1-\frac{1}{4}\right)\cdot...\cdot\left(1-\frac{1}{2017}\right)\)
\(=\frac{1}{2}\cdot\frac{2}{3}\cdot\frac{3}{4}\cdot..\cdot\frac{2016}{2017}\)
\(=\frac{1}{2017}\)
c) \(A=2000-5-5-5-..-5\)(có 200 số 5)
\(A=2000-\left(5\cdot200\right)\)
\(A=2000-1000\)
\(A=1000\)
a) \(\left(\frac{3}{5}.\frac{5}{3}\right).\frac{8}{27}\)
= \(1.\frac{8}{27}\)
=\(\frac{8}{27}\)
b) \(\frac{7}{19}.\left(\frac{1}{3}.\frac{2}{3}\right)\)
= \(\frac{7}{19}.\frac{2}{9}\)
=\(\frac{14}{81}\)
Không biết có đúng không? Tick mình nha !
(9/2-2xX):11/7=77/20
9/2-2xX=121/20
2xX=-31/20
X=-31/40
k mk nha mk đung đó
\(\left(\frac{9}{2}-2\times x\right):1\frac{4}{7}=\frac{11}{4}\times\frac{7}{5}\)
\(\left(\frac{9}{2}-2\times x\right):\frac{11}{7}=\frac{77}{20}\)
\(\frac{9}{2}-2\times x=\frac{77}{20}\times\frac{11}{7}\)
\(\frac{9}{2}-2\times x=\frac{121}{20}\)
\(2\times x=\frac{9}{2}-\frac{121}{20}\)
\(2x=\frac{-31}{20}\)
\(x=\frac{-31}{20}:2\)
\(x=\frac{-31}{40}\)
giúp mk xem lại đề chút nha! vì lớp 5 chưa học số âm!