The problem asks to find the truth set of two equations. The equations are: (i) $4^{\sqrt{x}} = 8^{2x}$ (ii) $(3^y) \cdot (\frac{1}{27})^y = 81$

AlgebraExponential EquationsSolving EquationsRadical Equations
2025/3/10

1. Problem Description

The problem asks to find the truth set of two equations. The equations are:
(i) 4x=82x4^{\sqrt{x}} = 8^{2x}
(ii) (3y)(127)y=81(3^y) \cdot (\frac{1}{27})^y = 81

2. Solution Steps

(i) Solve 4x=82x4^{\sqrt{x}} = 8^{2x}
First, rewrite both sides with the same base,

2. $4 = 2^2$ and $8 = 2^3$.

So the equation becomes:
(22)x=(23)2x(2^2)^{\sqrt{x}} = (2^3)^{2x}
22x=26x2^{2\sqrt{x}} = 2^{6x}
Since the bases are equal, equate the exponents:
2x=6x2\sqrt{x} = 6x
x=3x\sqrt{x} = 3x
Square both sides:
x=9x2x = 9x^2
9x2x=09x^2 - x = 0
x(9x1)=0x(9x - 1) = 0
So x=0x = 0 or 9x1=09x - 1 = 0, which means x=19x = \frac{1}{9}.
Check the solutions:
If x=0x=0, 40=40=14^{\sqrt{0}} = 4^0 = 1 and 82(0)=80=18^{2(0)} = 8^0 = 1. So x=0x=0 is a solution.
If x=19x=\frac{1}{9}, 419=413=(22)13=2234^{\sqrt{\frac{1}{9}}} = 4^{\frac{1}{3}} = (2^2)^{\frac{1}{3}} = 2^{\frac{2}{3}} and 82(19)=829=(23)29=269=2238^{2(\frac{1}{9})} = 8^{\frac{2}{9}} = (2^3)^{\frac{2}{9}} = 2^{\frac{6}{9}} = 2^{\frac{2}{3}}. So x=19x=\frac{1}{9} is a solution.
(ii) Solve (3y)(127)y=81(3^y) \cdot (\frac{1}{27})^y = 81
Rewrite the equation:
3y(271)y=813^y \cdot (27^{-1})^y = 81
3y(33)y=343^y \cdot (3^{-3})^y = 3^4
3y33y=343^y \cdot 3^{-3y} = 3^4
3y3y=343^{y - 3y} = 3^4
32y=343^{-2y} = 3^4
Since the bases are equal, equate the exponents:
2y=4-2y = 4
y=2y = -2

3. Final Answer

x=0,19x = 0, \frac{1}{9}
y=2y = -2

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