Answer:
[tex]x = -9[/tex]
Step-by-step explanation:
Given equation:
[tex]25^{2x+3} = 125^{2x+8}[/tex]
Convert 25 and 125 to base 5:
[tex]\implies (5^2)^{2x+3} = (5^3)^{2x+8}[/tex]
Apply exponent rule [tex](a^b)^c=a^{bc}[/tex]
[tex]\implies 5^{2(2x+3)} = 5^{3(2x+8)}[/tex]
If [tex]a^{f(x)}=a^{g(x)}[/tex] then [tex]f(x)=g(x)[/tex]:
[tex]\implies 2(2x+3) = 3(2x+8)[/tex]
Expand:
[tex]\implies 4x+6 = 6x+24[/tex]
Subtract 6x from both sides:
[tex]\implies -2x+6 = 24[/tex]
Subtract 6 from both sides:
[tex]\implies -2x=18[/tex]
Divide both sides by -2:
[tex]\implies x=-9[/tex]
Let's solve up
[tex]\\ \rm\rightarrowtail 25^{2x+3}=125^{2x+8}[/tex]
[tex]\\ \rm\rightarrowtail 5^{2(2x+3)}=5^{3(2x+8)}[/tex]
[tex]\\ \rm\rightarrowtail 5^{4x+6}=5^{6x+24}[/tex]
[tex]\\ \rm\rightarrowtail 4x+6=6x+24[/tex]
[tex]\\ \rm\rightarrowtail -18=2x[/tex]
[tex]\\ \rm\rightarrowtail x=-9[/tex]
