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Algebra Level 2

2 x + 2 x + 2 x + 2 x + 2 = 112 \large 2^x + 2^x + 2^x + 2^{x+2}= 112 Find x x .

16 16 There are no solutions 4 4 112 112 2 x + 2 2^{x+2} 2 x 2^x

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3 solutions

Kay Xspre
Mar 3, 2016

7 ( 2 x ) = 112 x = l o g 2 ( 112 7 ) = 4 7(2^x) = 112\Rightarrow x = log_2 (\frac{112}{7}) = 4

Munem Shahriar
Aug 15, 2017

2 x + 2 x + 2 x + 2 x + 2 = 112 2^x + 2^x + 2^x + 2^{x+2} = 112

Factorizing 2 x + 2 x + 2 x + 2 x + 2 2^x + 2^x + 2^x + 2^{x+2}

2 x + 2 x + 2 x + 2 x + 2 2^x + 2^x + 2^x + 2^{x+2}

2 x + 2 0 2 x + 2 0 2 x + 2 2 2 x 2^x + 2^0 \cdot 2^x + 2^0 \cdot 2^x + 2^2 \cdot 2^x

= 2 x ( 1 + 2 0 + 2 0 + 2 2 ) = 2^x(1+2^0+2^0+2^2)

= 7 2 x = 7 \cdot 2^x

Now,

7 2 x = 112 7 \cdot 2^x =112

2 x = 16 2^x = 16

Convert 16 to base 2.

2 x = 2 4 2^x = 2^4 ~ ~ ~ ~ ~~ ~ ~ ; 16 = 2 4 ;16 = 2^4

x = 4 x = \boxed{4}

2 x + 2 x + 2 x + 2 x + 2 = 112 2^x+2^x+2^x+2^{x+2}=112

3 ( 2 x ) + 2 x ( 2 2 ) = 112 3(2^x)+2^x(2^2)=112

2 x ( 3 + 4 ) = 112 2^x(3+4)=112

2 x ( 7 ) = 112 2^x(7)=112

2 x = 112 7 2^x=\dfrac{112}{7}

2 x = 16 2^x=16

2 x = 2 4 2^x=2^4

x = 4 \color{#D61F06}\boxed{x=4}

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