Question

TÌM X BIẾT : 2^(x) + 2^(x+1) + 2^(x+2) = 960 - 2^(x+ 3)

Answer 1

\(2^x+2^{x+1}+2^{x+2}=960-2^{x+3}\)

\(\Leftrightarrow 2^x+2^x.2+2^x.2^2.2^3=960\)

\(\Leftrightarrow 2^x(1+2+2^2+2^3)=960\)

\(\Leftrightarrow 2^x(1+2+4+8)=960\)

\(\Leftrightarrow 2^x.15=960 \)

\(\Leftrightarrow 2^x=64\)

\(\Leftrightarrow 2^x=2^6\)

Vậy: x = 6

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