720:[41-(2×x-5)]=120
[41-(2×x-5)]=720:120
[41-(2×x-5)]=6
(2×x-5)=41-6
(2×x-5)=35
2×x=35+5
2x=40
x=40:2
vậy x=20
a) \(720:\left[41-\left(2x-5\right)\right]=120\)
\(\Rightarrow\left[41-\left(2.x-5\right)\right]=6\)
\(\Rightarrow2x-5=35\Rightarrow2x=40\Rightarrow x=20\)
b) \(4,8.5-x+100=250\)
\(\Rightarrow4,8.5-x=150\Rightarrow24-x=150\Rightarrow x=-126\)
c)+) \(\frac{3}{5}+\frac{2}{5}:x=1\Rightarrow\frac{2}{5}:x=\frac{2}{5}\Rightarrow x=1\)
+) \(\frac{3}{5}+\frac{2}{5}:x=\frac{1}{4}\Rightarrow\frac{2}{5}:x=\frac{-7}{20}\Rightarrow x=\frac{-8}{7}\)
Cậu có thể tham khảo bài làm trên đây ạ, chúc cậu hok tốt ^^
2. Tìm x:
a) 720: [41-(2.x-5)] = 120 b) 4,8.5-x+100 = 250 c) 3/5 +2/5:x =1 và 1/4
[41-(2.x-5)] = 720:120 24-x+100 =250 3/5 + 2/5 :x = 5/4
[41-(2.x-5)] = 6 24-x = 250 -100 2/5:x = 5/4 - 3/5
(2.x-5) = 41-6 24-x = 150 2/5:x = 25/20 - 12/20
(2.x-5) = 35 x = 150 - 24 2/5:x = 13/20
2.x = 35+5 x = 126 x = 2/5:13/20
2.x = 40 x = 8/20 : 13/20
x = 40: 2 = 20 x = 8/13
\(a,720:\left[41-\left(2\times x-5\right)\right]=120\)
\(41-\left(2\times x-5\right)=720:120\)
\(2\times x-5=41-6\)
\(2\times x-5=35\)
\(2\times x=35+5\)
\(2\times x=40\)
\(x=40:2\)
\(x=20\)
\(b,4,8\times5-x+100=250\)
\(24-x=250-100\)
\(24-x=150\)
\(x=24-150\)
\(x=-126\)
\(c,\frac{3}{5}+\frac{2}{5}:x=1\frac{1}{4}\)
\(\frac{3}{5}+\frac{2}{5}:x=\frac{5}{4}\)
\(\frac{2}{5}:x=\frac{5}{4}-\frac{3}{5}\)
\(\frac{2}{5}:x=\frac{13}{20}\)
\(x=\frac{2}{5}:\frac{13}{20}\)
\(x=\frac{8}{13}\)
Học tốt
