đây là bài tìm x, nhớ giải từng bước nhé
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Gọi H=abc-cba
<=>H=100*a+10*b+c-100*c-10*b-c
<=>H=99*a-99*c
<=>H=99*(a-c) (1)
thay a-c=4 vào (1)
(1)<=> H=99*4=396
Vậy abc-cba=396
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b)\(5.5:x=\frac{13}{15}\)
\\(x=5.5:\frac{13}{15}=\frac{11}{2}x\frac{15}{13}=\frac{165}{26}\)
c)\(\left(\frac{3x}{7}+1\right):\left(-4\right)=-\frac{1}{28}\)
\(\frac{3x}{7}+1=\frac{1}{7}\)
\(\frac{3x}{7}=-\frac{6}{7}\)
\(\Rightarrow x=6:3=2\)
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\(\frac{x}{27}\)= \(\frac{-2}{3,6}\)
\(\Leftrightarrow\)\(x\cdot3,6=27\cdot-2\)
\(\Leftrightarrow\)\(x\cdot3,6=-54\)
\(\Leftrightarrow\)\(x=-\frac{54}{3,6}\)
\(\Rightarrow\)\(x=-15\)
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100a+10b+c=11a+11b+11c
89a=b+10c
vi b+10c<100
=>89a<100
=>a=1
89=b+10c
89-b=10c
Vi 10c chia het cho 10
89 -b có chia hết cho 10
=> b=9
=>10c=80
=>c=8
=> abc=198
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\(14\times74+14\times24+28\)
\(=14\times\left(74+24\right)+28\)
\(=14\times98+28\)
\(=1372+28\)
\(=1400\)
14.74 + 14.24 + 28
= 14.74 + 14.24 + 14.2
= 14.( 74 + 24 + 2)
= 14.100
= 1400
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45408 : x + 81664 : x = 722
( 45408 + 81664 ) : x = 722
127072 : x = 722
x = 127072 : 722
x = 176
đk : x khác 2
\(\Leftrightarrow\left(x-2\right)^2=100\)
\(\left[{}\begin{matrix}x-2=10\\x-2=-10\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=12\\x=-8\end{matrix}\right.\left(tm\right)\)
\(\dfrac{x-2}{50}=\dfrac{2}{x-2}\)
\(\Rightarrow\left(x-2\right).x-2=2.50\)
\(\Rightarrow\left(x-2\right).x-2=100\)
\(Ta\) có 10^2 thì bằng 100
Vậy x=10