ABC26GN1873 · Surds and Indices

Subject: General Aptitude · Chapter: Surds and Indices · Exam: · Marks: · Difficulty:

If $2^{x-1}+2^{x+1}=1280$, then find the value of $x$.
Answer
Answer (as printed):
Explanation
$2^{x-1}+2^{x+1}=1280 \Leftrightarrow 2^{x-1}\left(1+2^{2}\right)=1280 \Leftrightarrow 2^{x-1}=\frac{1280}{5}=256=2^{8} \Leftrightarrow x-1=8 \Leftrightarrow x=9$.

Explanation as extracted from the printed page; notation may be imperfect.

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