Question

Please help me for 15 points

Answer 1

Answer:

x=0 , x=-3

Step-by-step explanation:

Apply all exponent rules:

$3^{x+3}$ = $3^{x}$×$3^{3}$

$\frac{1}{3^{x} }$ = $(3^{x} )^{-1}$

Rewrite equation with $3^{x}= u$

$u$ × $3^{3}$ + $u^{-1}$ - 28 = 0

Solve for u to give :

u = 1, u = 1/27

Substitute back u = $3^{x}$, solve for x :

$3^{x}$ = 1 , x= 0

$3^{x}= \frac{1}{27}$ , x= -3  
x=0 , x=-3

Substituting x back into original equation verifies our answers