SOLUTION: 2^2x-3 — 2^2x-2 — 1 = 0

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Question 1210236: 2^2x-3 — 2^2x-2 — 1 = 0
Found 4 solutions by greenestamps, mccravyedwin, ikleyn, Edwin McCravy:
Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


Assuming the equation is 2%5E%282x-3%29-2%5E%282x-2%29-1=0....

Factor 2%5E%282x-3%29 out of the first two terms:

%282%5E%282x-3%29%29%281-2%29-1
%282%5E%282x-3%29%29%28-1%29-1

The expression 2%5E%282x-3%29 is always positive, so %282%5E%282x-3%29%29%28-1%29 is always negative; then subtracting 1 makes the expression more negative. So the given expression is never equal to 0. In fact, it should be clear that the value of the expression is always less than -1.

A graph shows this:

graph%28400%2C400%2C-5%2C5%2C-10%2C5%2C2%5E%282x-3%29-2%5E%282x-2%29-1%29

ANSWER: no solution


Answer by mccravyedwin(407) About Me  (Show Source):
You can put this solution on YOUR website!
2%5E%282x-3%29+-+2%5E%282x-2%29+-+1+=+0

2%5E%282x%29%2A2%5E%28-3%29+-+2%5E%282x%29%2A2%5E%28-2%29+-+1=0

let y=2%5E%282x%29

y%2A2%5E%28-3%29+-+y%2A2%5E%28-2%29+-+1=0

y%5E%22%22%2F2%5E3+-+y%5E%22%22%2F2%5E2+-+1=0

y%2F8+-+y%2F4+-+8=0

y-2y-8=0

-y-8=0

y%2B8=0

2%5E%282x%29%2B8=0

2%5E%282x%29+=+-8

There is no real solution.  Do you want complex solution(s)?

Normally if complex solutions are wanted, the variable is z, not x.

Edwin

Answer by ikleyn(52781) About Me  (Show Source):
You can put this solution on YOUR website!
.

One look at this equation is enough to see that it has no solutions in real numbers.

Indeed,  for any real value of  x,   2%5E%282x-3%29  is less than  2%5E%282x-2%29.

So,  the difference  2%5E%282x-3%29 - 2%5E%282x-2%29  is always negative.

When you subtract  1  from this negative number,  you get negative number lesser than  -1.

Thus,  left side of the equation can not be equal to zero.



Answer by Edwin McCravy(20055) About Me  (Show Source):
You can put this solution on YOUR website!
But it does have a complex solution

2%5E%282x-3%29+-+2%5E%282x-2%29+-+1+=+0

2%5E%282x%29%2A2%5E%28-3%29+-+2%5E%282x%29%2A2%5E%28-2%29+-+1=0

let y=2%5E%282x%29

y%2A2%5E%28-3%29+-+y%2A2%5E%28-2%29+-+1=0

y%5E%22%22%2F2%5E3+-+y%5E%22%22%2F2%5E2+-+1=0

y%2F8+-+y%2F4+-+8=0

y-2y-8=0

-y-8=0

y%2B8=0

2%5E%282x%29%2B8=0

2%5E%282x%29+=+-8

Since e%5E%28x%2Ai%29=cos%28x%29%2Bi%2Asin%28x%29 by one of many of Euler's equations.

e%5E%28pi%2Ai%29=cos%28pi%29%2Bi%2Asin%28pi%29

e%5E%28pi%2Ai%29=%28-1%29%2Bi%2A0=-1

2%5E%282x%29+=+e%5E%28pi%2Ai%29%2A8

2%5E%282x%29+=+e%5E%28pi%2Ai%29%2A2%5E3

2%5E%282x-3%29+=+e%5E%28pi%2Ai%29

Take natural logs of both sides:

ln%282%5E%282x-3%29%29+=+ln%28e%5E%28pi%2Ai%29%29

%282x-3%29%2Aln%282%29+=+pi%2Ai

2x%2Aln%282%29-3%2Aln%282%29+=+pi%2Ai

2x%2Aln%282%29+=+3ln%282%29%2Bpi%2Ai

x+=+%283ln%282%29%2Bpi%2Ai%29%2F%282ln%282%29%29

x+=+3%2F2%2B+expr%28pi%2F%282ln%282%29%29%29%2Ai

Edwin