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\(42-2\left(32-2^{x+1}\right)=10\)
\(\Leftrightarrow2\left(32-2^{x+1}\right)=42-10=32\)
\(\Leftrightarrow32-2^{x+1}=16\)
\(\Leftrightarrow2^{x+1}=32-16=16\)
\(\Leftrightarrow2^{x+1}=2^4\)
\(\Leftrightarrow x+1=4\)
\(\Rightarrow x=3\)
\(42-2\left(32-2^{x+1}\right)=10\)
\(\Leftrightarrow2^{x+1}=16\)
\(\Leftrightarrow2^{x+1}=2^4\)
=> x = 4
\(42-2.\left(32-2^{x+1}\right)=10\)
\(2.\left(32-2^{x+1}\right)=42-10\)
\(2.\left(32-2^{x+1}\right)=32\)
\(32-2^{x+1}=32:2\)
\(32-2^{x+1}=16\)
\(2^{x+1}=32-16\)
\(2^{x+1}=16\)
\(2^{x+1}=2^4\)
\(x+1=4\)
\(x=4-1\)
\(x=3\)
\(\frac{7}{x}=\frac{y}{81}=-\frac{42}{54}\)
\(+,\frac{7}{x}=-\frac{42}{54}\Rightarrow378=-42x\Rightarrow x=-9\)
\(+,\frac{y}{81}=-\frac{42}{54}\Rightarrow54y=-3402\Rightarrow y=-63\)
a) B (13) = { 13 ; 26 ; 39 ; 52 ;......}
mà 0 < x < 42
=>x={13; 26 ; 39 }
Ư(72)={1;2;3;4;6;8;9;12;18;24;36;72}
mà x > 9
=> x={12;18;24;36;72}
\(32x-42=-10x+42\)
\(\Leftrightarrow32x+10x=42+42\)
\(\Leftrightarrow42x=84\)
\(\Leftrightarrow x=2\)