tolong bantu please [tex]jika \frac{2 ^{a + 2} + 2 ^{ a+ 4} + 2 ^{a + 6}}{128} = \frac{21}{2} \: maka \: a \: = [/tex]

Nilai a adalah 4. Semoga membantu dan mudah dimengerti. Selamat belajar.

[tex] \frac{ {2}^{a + 2 } + {2}^{a + 4} + {2}^{a + 6} }{128} = \frac{21}{2} \\ \frac{ ({2}^{a}. {2}^{2}) + ( {2}^{a} . {2}^{4}) + ( {2}^{a}. {2}^{6}) }{128} = \frac{21}{2} \\ \frac{4( {2}^{a} ) + 16( {2}^{a} ) + 64( {2}^{a} )}{128} = \frac{21}{2} \\ \frac{ {2}^{a} (4 + 16 + 64)}{128} = \frac{21}{2} \\ \frac{84( {2}^{a} )}{128} = \frac{21}{2} \\ (2)(84)( {2}^{a} ) =(21)(128) \\ (168)( {2}^{a} ) = 2688 \\ {2}^{a} = \frac{2688}{168} \\ {2}^{a} = 16 \\ {2}^{a} = {2}^{4} \\ maka \\ a = 4[/tex]