3^x+3^x-1+3^x-2+3^x-3=4,5 la ecuación
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Solución
Solución detallada
Tenemos la ecuación:
( 3 x + ( ( 3 x + ( ( 3 x + 3 x ) − 1 ) ) − 2 ) ) − 3 = 9 2 \left(3^{x} + \left(\left(3^{x} + \left(\left(3^{x} + 3^{x}\right) - 1\right)\right) - 2\right)\right) - 3 = \frac{9}{2} ( 3 x + ( ( 3 x + ( ( 3 x + 3 x ) − 1 ) ) − 2 ) ) − 3 = 2 9 o
( ( 3 x + ( ( 3 x + ( ( 3 x + 3 x ) − 1 ) ) − 2 ) ) − 3 ) − 9 2 = 0 \left(\left(3^{x} + \left(\left(3^{x} + \left(\left(3^{x} + 3^{x}\right) - 1\right)\right) - 2\right)\right) - 3\right) - \frac{9}{2} = 0 ( ( 3 x + ( ( 3 x + ( ( 3 x + 3 x ) − 1 ) ) − 2 ) ) − 3 ) − 2 9 = 0 o
4 ⋅ 3 x = 21 2 4 \cdot 3^{x} = \frac{21}{2} 4 ⋅ 3 x = 2 21 o
3 x = 21 8 3^{x} = \frac{21}{8} 3 x = 8 21 - es la ecuación exponencial más simple
Sustituimos
v = 3 x v = 3^{x} v = 3 x obtendremos
v − 21 8 = 0 v - \frac{21}{8} = 0 v − 8 21 = 0 o
v − 21 8 = 0 v - \frac{21}{8} = 0 v − 8 21 = 0 Transportamos los términos libres (sin v)
del miembro izquierdo al derecho, obtenemos:
v = 21 8 v = \frac{21}{8} v = 8 21 Obtenemos la respuesta: v = 21/8
hacemos cambio inverso
3 x = v 3^{x} = v 3 x = v o
x = log ( v ) log ( 3 ) x = \frac{\log{\left(v \right)}}{\log{\left(3 \right)}} x = log ( 3 ) log ( v ) Entonces la respuesta definitiva es
x 1 = log ( 21 8 ) log ( 3 ) = log ( ( 21 8 ) 1 log ( 3 ) ) x_{1} = \frac{\log{\left(\frac{21}{8} \right)}}{\log{\left(3 \right)}} = \log{\left(\left(\frac{21}{8}\right)^{\frac{1}{\log{\left(3 \right)}}} \right)} x 1 = log ( 3 ) log ( 8 21 ) = log ( ( 8 21 ) l o g ( 3 ) 1 )
Gráfica
-12.5 -10.0 -7.5 -5.0 -2.5 0.0 2.5 5.0 7.5 10.0 12.5 15.0 -500000 1000000
Suma y producto de raíces
[src]
/ 1 \
| ------|
| log(3)|
log\21/8 /
log ( ( 21 8 ) 1 log ( 3 ) ) \log{\left(\left(\frac{21}{8}\right)^{\frac{1}{\log{\left(3 \right)}}} \right)} log ( ( 8 21 ) l o g ( 3 ) 1 )
/ 1 \
| ------|
| log(3)|
log\21/8 /
log ( ( 21 8 ) 1 log ( 3 ) ) \log{\left(\left(\frac{21}{8}\right)^{\frac{1}{\log{\left(3 \right)}}} \right)} log ( ( 8 21 ) l o g ( 3 ) 1 )
/ 1 \
| ------|
| log(3)|
log\21/8 /
log ( ( 21 8 ) 1 log ( 3 ) ) \log{\left(\left(\frac{21}{8}\right)^{\frac{1}{\log{\left(3 \right)}}} \right)} log ( ( 8 21 ) l o g ( 3 ) 1 )
/ 1 \
| ------|
| log(3)|
log\21/8 /
log ( ( 21 8 ) 1 log ( 3 ) ) \log{\left(\left(\frac{21}{8}\right)^{\frac{1}{\log{\left(3 \right)}}} \right)} log ( ( 8 21 ) l o g ( 3 ) 1 )
/ 1 \
| ------|
| log(3)|
x1 = log\21/8 /
x 1 = log ( ( 21 8 ) 1 log ( 3 ) ) x_{1} = \log{\left(\left(\frac{21}{8}\right)^{\frac{1}{\log{\left(3 \right)}}} \right)} x 1 = log ( ( 8 21 ) l o g ( 3 ) 1 )
x1 = log((21/8)^(1/log(3)))