What is the answer to 7^{2x+3}-8*7^{x+1}+1=0 ?

The answer to 7^{2x+3}-8*7^{x+1}+1=0 is x=-1,x=-2

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7^{2x+3}-8*7^{x+1}+1=0

7^{2 x + 3} - 8 \cdot 7^{x + 1} + 1 = 0

x = - 1, x = - 2

Solution steps

7^{2 x + 3} - 8 \cdot 7^{x + 1} + 1 = 0

Apply exponent rules

(7^{x})^{2} \cdot 7^{3} - 8 \cdot 7^{x} \cdot 7^{1} + 1 = 0

Rewrite the equation with

7^{x} = u

(u)^{2} \cdot 7^{3} - 8 u \cdot 7^{1} + 1 = 0

Solve

u^{2} \cdot 7^{3} - 8 u \cdot 7^{1} + 1 = 0 : u = \frac{1}{7}, u = \frac{1}{49}

u = \frac{1}{7}, u = \frac{1}{49}

Substitute back

u = 7^{x},

solve for

x

Solve

7^{x} = \frac{1}{7} : x = - 1

Solve

7^{x} = \frac{1}{49} : x = - 2

x = - 1, x = - 2

e^{(l n (0.8)) t} = 0.9

(0.5)^{\frac{9900}{x}} = 0

0 = e^{- x^{2}}

\frac{1}{64} = 1 6^{2 a}

(1 0^{x} - 1) (1 0^{x} + 1) = 0

What is the answer to 7^{2x+3}-8*7^{x+1}+1=0 ?
The answer to 7^{2x+3}-8*7^{x+1}+1=0 is x=-1,x=-2
Solve for x: 7^{2x+3}-8*7^{x+1}+1=0
The solution is x=-1,x=-2