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a) đặt [41-(2x-5)] là a <=> 1440 : a = 48
=> a = 30 <=> [41-(2x-5)] = 30 => 41-(2x-5) =30
<=> -(2x-5) = -11 <=> 2x-5 = 11 <=> 2x = 16 <=> x=2
b) tương tự câu a
gợi ý đáp án : x = 210
1440:[41-(2x-5)]=24.3
1440 : [41 - (2x - 5 ) ] = 48
41 - (2x - 5 ) = 1440 : 48
41 - ( 2x - 5 ) = 30
2x - 5 = 41 - 30
2x - 5 = 11
2x = 11 + 5
2x = 16
x= 16 : 2
x = 8
a ) \(\left(19x+2,5^2\right)\div14=\left(13-8\right)^2-4^2\)
\(\Rightarrow\left(19x+50\right)\div14=5^2-16\)
\(\Rightarrow\left(19+50\right)\div14=25-16=9\)
\(\Rightarrow19x+50=9\times14\)
\(\Rightarrow19x+50=126\)
\(\Rightarrow19x=126-50\)
\(\Rightarrow19x=76\)
\(\Rightarrow x=4\)
b ) \(1440\div\left[41-\left(2x-5\right)\right]=2^4.3\)
\(\Leftrightarrow1440\div\left[41-\left(2x-5\right)\right]=48\)
\(\Leftrightarrow41-\left(2x-5\right)=30\)
\(\Leftrightarrow2x-5=11\)
\(\Leftrightarrow2x=16\)
\(\Leftrightarrow x=8\)
\(1440:\left[41-\left(2x-5\right)\right]=2^4.3\)
\(\Rightarrow1440:\left[41-\left(2x-5\right)\right]=48\)
\(\Rightarrow41-\left(2x-5\right)=30\)
\(\Rightarrow2x-5=11\)
\(\Rightarrow2x=16\)
\(\Rightarrow x=8\)
Vậy \(x=8\)
\(\frac{1440}{41-\left(x-5\right)}=2^4.3\)
\(\Rightarrow\left[41-\left(x-5\right)\right]2^4.3=1440\)
\(\Rightarrow\left[41-\left(x-5\right)\right].48=1440\)
\(\Rightarrow41-\left(x-5\right)=30\)
\(\Rightarrow x-5=11\)
\(\Rightarrow x=16\)
Vậy \(x=16\)
1e) Để \(\frac{2x-1}{x-3}\) nguyên thì \(2x-1⋮x-3\)
\(\Leftrightarrow2x-6+5⋮x-3\)
\(\Leftrightarrow2\left(x-3\right)+5⋮x-3\)
Do \(2\left(x-3\right)⋮x-3\) \(\Rightarrow5⋮x-3\)
\(\Rightarrow x-3\in\left\{-5;-1;1;5\right\}\)
\(\Leftrightarrow x\in\left\{-2;2;4;8\right\}\)
Vậy:...................
a) 1440: [41-{2x-5}]=16.3
41-(2x-5)=1440-48
41-(2x-5)=1392
2x-5=41-1392
2x-5=-1351
2x=-1351+5
2x=-1346
x=(-1346):2
x=-673