Hello, can someone help me with this tasks?

1.)

\(\log _2\left(x\right)-\log _4\left(y\right)=0 \)

\(5x^2-y^2=4 \)

2.)

\(64\cdot 9^x-84\cdot 12^x+27\cdot 16^x=0 \)

Guest Jun 18, 2018

edited by
Guest
Jun 18, 2018

#1**+1 **

2)

Solve for x:

64 9^x - 7 12^(x + 1) + 27 16^x = 0

The left hand side factors into a product with two terms:

(16 3^x - 9 4^x) (4 3^x - 3 4^x) = 0

Split into two equations:

16 3^x - 9 4^x = 0 or 4 3^x - 3 4^x = 0

Add 9 4^x to both sides:

16 3^x = 9 4^x or 4 3^x - 3 4^x = 0

9 4^x = 2^(2 x)·3^2:

2^4·3^x = 2^(2 x)·3^2 or 4 3^x - 3 4^x = 0

Equate exponents of 2 and 3 on both sides:

4 = 2 x and x = 2 or 4 3^x - 3 4^x = 0

All equations give x = 2 as the solution:

x = 2 or 4 3^x - 3 4^x = 0

Add 3 4^x to both sides:

x = 2 or 4 3^x = 3 4^x

3 4^x = 2^(2 x)·3^1:

x = 2 or 2^2·3^x = 2^(2 x)·3^1

Equate exponents of 2 and 3 on both sides:

x = 2 or 2 = 2 x and x = 1

All equations give x = 1 as the solution:

**x = 2 or x = 1**

Guest Jun 18, 2018

#2**+1 **

1)

Log_2(x) - Log_4(y) = 0....................(1)

5x^2 - y^2 =4..................................(2)

x = ± sqrt(y^2 + 4)/sqrt(5) sub this into (1) above.

Solve for y:

log(sqrt(y^2 + 4)/sqrt(5))/log(2) - log(y)/log(4) = 0

Bring log(sqrt(y^2 + 4)/sqrt(5))/log(2) - log(y)/log(4) together using the common denominator log(2) log(4):

(log(4) log(sqrt(y^2 + 4)/sqrt(5)) - log(2) log(y))/(log(2) log(4)) = 0

Multiply both sides by log(2) log(4):

log(4) log(sqrt(y^2 + 4)/sqrt(5)) - log(2) log(y) = 0

log(4) log(sqrt(y^2 + 4)/sqrt(5)) - log(2) log(y) = log(y^(-log(2))) + log(5^(-log(2)) (y^2 + 4)^log(2)) = log(5^(-log(2)) y^(-log(2)) (y^2 + 4)^log(2)):

log(5^(-log(2)) y^(-log(2)) (y^2 + 4)^log(2)) = 0

Cancel logarithms by taking exp of both sides:

5^(-log(2)) y^(-log(2)) (y^2 + 4)^log(2) = 1

Multiply both sides by 5^log(2):

y^(-log(2)) (y^2 + 4)^log(2) = 5^log(2)

Factor out the common power log(2) from the left hand side:

((y^2 + 4)/y)^log(2) = 5^log(2)

Raise both sides to the power of 1/log(2):

(y^2 + 4)/y = 5

Multiply both sides by y:

y^2 + 4 = 5 y

Subtract 5 y from both sides:

y^2 - 5 y + 4 = 0

The left hand side factors into a product with two terms:

(y - 4) (y - 1) = 0

Split into two equations:

y - 4 = 0 or y - 1 = 0

Add 4 to both sides:

y = 4 or y - 1 = 0

Add 1 to both sides:

**y = 4 or y = 1 and x =+or- 2 or x=+or- 1**

Guest Jun 18, 2018