What is the answer to 49^x-6*7^x-7=0 ?

The answer to 49^x-6*7^x-7=0 is x=1

English

Español

Português

Français

Deutsch

Italiano

Русский

中文(简体)

한국어

日本語

Tiếng Việt

עברית

العربية

Popular >

49^x-6*7^x-7=0

4 9^{x} - 6 \cdot 7^{x} - 7 = 0

x = 1

Solution steps

4 9^{x} - 6 \cdot 7^{x} - 7 = 0

Apply exponent rules

(7^{x})^{2} - 6 \cdot 7^{x} - 7 = 0

Rewrite the equation with

7^{x} = u

(u)^{2} - 6 u - 7 = 0

Solve

u^{2} - 6 u - 7 = 0 : u = 7, u = - 1

u = 7, u = - 1

Substitute back

u = 7^{x},

solve for

x

Solve

7^{x} = 7 : x = 1

Solve

7^{x} = - 1 :

No Solution for

x \in R

x = 1

8 1^{2 x + 3} = 9^{3 x + 1}

2^{2 x - 1} = 8

2^{n} = 64

- 10 e^{- x} = 0

3^{4 x - 9} = \frac{1}{243}