How do I solve 2x + 2-x = 6? I can't seem to find a way to get x isolated.
WHY DON'T WRITE IT AS SUCH?!!!!!!!!!!!!!!!!. You mean:
2^x + 2^-x=6???????????????????????????
Solve for x over the real numbers:
2^(-x)+2^x = 6
Simplify and substitute y = 2^x:
2^(-x)+2^x = 1/2^x+2^x = y+1/y = 6:
y+1/y = 6
Bring y+1/y together using the common denominator y:
(y^2+1)/y = 6
Multiply both sides by y:
y^2+1 = 6 y
Subtract 6 y from both sides:
y^2-6 y+1 = 0
Subtract 1 from both sides:
y^2-6 y = -1
Add 9 to both sides:
y^2-6 y+9 = 8
Write the left hand side as a square:
(y-3)^2 = 8
Take the square root of both sides:
y-3 = 2 sqrt(2) or y-3 = -2 sqrt(2)
Add 3 to both sides:
y = 3+2 sqrt(2) or y-3 = -2 sqrt(2)
Substitute back for y = 2^x:
2^x = 3+2 sqrt(2) or y-3 = -2 sqrt(2)
Take the logarithm base 2 of both sides:
x = (log(3+2 sqrt(2)))/(log(2)) or y-3 = -2 sqrt(2)
Add 3 to both sides:
x = (log(3+2 sqrt(2)))/(log(2)) or y = 3-2 sqrt(2)
Substitute back for y = 2^x:
x = (log(3+2 sqrt(2)))/(log(2)) or 2^x = 3-2 sqrt(2)
Take the logarithm base 2 of both sides:
Answer: |
| x = (log(3+2 sqrt(2)))/(log(2)) or x = (log(3-2 sqrt(2)))/(log(2))
The equation deals with variables as exponents. Thank you for trying to help, though.
WHY DON'T WRITE IT AS SUCH?!!!!!!!!!!!!!!!!. You mean:
2^x + 2^-x=6???????????????????????????
Solve for x over the real numbers:
2^(-x)+2^x = 6
Simplify and substitute y = 2^x:
2^(-x)+2^x = 1/2^x+2^x = y+1/y = 6:
y+1/y = 6
Bring y+1/y together using the common denominator y:
(y^2+1)/y = 6
Multiply both sides by y:
y^2+1 = 6 y
Subtract 6 y from both sides:
y^2-6 y+1 = 0
Subtract 1 from both sides:
y^2-6 y = -1
Add 9 to both sides:
y^2-6 y+9 = 8
Write the left hand side as a square:
(y-3)^2 = 8
Take the square root of both sides:
y-3 = 2 sqrt(2) or y-3 = -2 sqrt(2)
Add 3 to both sides:
y = 3+2 sqrt(2) or y-3 = -2 sqrt(2)
Substitute back for y = 2^x:
2^x = 3+2 sqrt(2) or y-3 = -2 sqrt(2)
Take the logarithm base 2 of both sides:
x = (log(3+2 sqrt(2)))/(log(2)) or y-3 = -2 sqrt(2)
Add 3 to both sides:
x = (log(3+2 sqrt(2)))/(log(2)) or y = 3-2 sqrt(2)
Substitute back for y = 2^x:
x = (log(3+2 sqrt(2)))/(log(2)) or 2^x = 3-2 sqrt(2)
Take the logarithm base 2 of both sides:
Answer: |
| x = (log(3+2 sqrt(2)))/(log(2)) or x = (log(3-2 sqrt(2)))/(log(2))
2^x + 2^(-x) = 6 rewrite as
2^x + 1 / [2^x) = 6 multiply through by 2^x
[2^x][2^x] + 1 = 6[2^x] subtract 6[2^x] from both sides
[2^x]^2 -+ 1 - 6[2^x] = 0 let 2^x = a ..... and we have.....
a^2 + 1 - 6a = 0 rearrange
a^2 - 6a + 1 = 0
Using the quadratic formula to solve for a, we have .......a = 3-2 sqrt(2) or a = 3 + 2sqrt(2)
Thus a = 2^x
And we have that
2^x = 3 - sqrt(2) take the log of both sides
log2^x = log [3 -2 sqrt(2) ] and by a log property, we can write
x*log(2) = log[ 3 - 2sqrt(2)] divide both sides by log(2)
x = log[3 - 2sqrt(2)] / log(2) = about -2.5431
In similar fashion, x also equals.....
log[ 3 + 2sqrt(2)] / log(2) = about 2.5431
Here's a graph of both sides of this strange equation with the intersection points being the solutions.....
https://www.desmos.com/calculator/uomirk7pas