We notice that 25^sqrt(x+1) =
5^2sqrt(x+1)
We can replace 5^sqrt(x+1) by
t:
The equation will
become:
t^2 + 5 = 6t
We'll
shift all terms to the left:
t^2 - 6t + 5 =
0
We'll apply quadratic
formula:
t1 =
[6+sqrt(36-20)]/2
t1 =
(6+sqrt16)/2
t1 =(6+4)/2
t1 =
5
t2 = 1
But t1 = 5^sqrt(x+1)
=> 5 = 5^sqrt(x+1)
Since the bases are matching,
we'll apply one to one rule:
sqrt(x+1) = 1
We'll
raise to square both sides:
x + 1 = 1 => x =
0
t2 = 5^sqrt(x+1) => 1 = 5^sqrt(x+1), where 1 =
5^0
Since the bases are matching, we'll apply again one to
one rule:
sqrt(x+1) = 0
x + 1 = 0 => x =
-1
Both value are valid, therefore the
solutions of the equation are {-1 ; 0}.
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