Can i perform this step?
up vote
2
down vote
favorite
a,b $in$ R
$${5^{a-b}}cdot{27^{-(a+b)}}={5^1}cdot {27^1} Rightarrow a^{2}-b^{2}=?$$
My Solution:
$a-b=1$
$a+b=-1$ then $a=0$ ; $b=-1$
Since $a$ and $b$ are not whole numbers, I believe, I cannot perform above solution. Am I right?
algebra-precalculus
add a comment |
up vote
2
down vote
favorite
a,b $in$ R
$${5^{a-b}}cdot{27^{-(a+b)}}={5^1}cdot {27^1} Rightarrow a^{2}-b^{2}=?$$
My Solution:
$a-b=1$
$a+b=-1$ then $a=0$ ; $b=-1$
Since $a$ and $b$ are not whole numbers, I believe, I cannot perform above solution. Am I right?
algebra-precalculus
2
You are right, you cannot do that step since $a$ and $b$ are real numbers.
– Anurag A
Nov 22 at 18:41
3
@idea that’s not true. $5^x=7$ has a solution $x=log_57$.
– Anurag A
Nov 22 at 18:43
1
To debug an incorrect argument replace $27$ by $25 = 5^2$ and notice what goes wrong when you apply the same argument.
– Bill Dubuque
Nov 22 at 18:51
add a comment |
up vote
2
down vote
favorite
up vote
2
down vote
favorite
a,b $in$ R
$${5^{a-b}}cdot{27^{-(a+b)}}={5^1}cdot {27^1} Rightarrow a^{2}-b^{2}=?$$
My Solution:
$a-b=1$
$a+b=-1$ then $a=0$ ; $b=-1$
Since $a$ and $b$ are not whole numbers, I believe, I cannot perform above solution. Am I right?
algebra-precalculus
a,b $in$ R
$${5^{a-b}}cdot{27^{-(a+b)}}={5^1}cdot {27^1} Rightarrow a^{2}-b^{2}=?$$
My Solution:
$a-b=1$
$a+b=-1$ then $a=0$ ; $b=-1$
Since $a$ and $b$ are not whole numbers, I believe, I cannot perform above solution. Am I right?
algebra-precalculus
algebra-precalculus
asked Nov 22 at 18:36
Eldar Rahimli
385
385
2
You are right, you cannot do that step since $a$ and $b$ are real numbers.
– Anurag A
Nov 22 at 18:41
3
@idea that’s not true. $5^x=7$ has a solution $x=log_57$.
– Anurag A
Nov 22 at 18:43
1
To debug an incorrect argument replace $27$ by $25 = 5^2$ and notice what goes wrong when you apply the same argument.
– Bill Dubuque
Nov 22 at 18:51
add a comment |
2
You are right, you cannot do that step since $a$ and $b$ are real numbers.
– Anurag A
Nov 22 at 18:41
3
@idea that’s not true. $5^x=7$ has a solution $x=log_57$.
– Anurag A
Nov 22 at 18:43
1
To debug an incorrect argument replace $27$ by $25 = 5^2$ and notice what goes wrong when you apply the same argument.
– Bill Dubuque
Nov 22 at 18:51
2
2
You are right, you cannot do that step since $a$ and $b$ are real numbers.
– Anurag A
Nov 22 at 18:41
You are right, you cannot do that step since $a$ and $b$ are real numbers.
– Anurag A
Nov 22 at 18:41
3
3
@idea that’s not true. $5^x=7$ has a solution $x=log_57$.
– Anurag A
Nov 22 at 18:43
@idea that’s not true. $5^x=7$ has a solution $x=log_57$.
– Anurag A
Nov 22 at 18:43
1
1
To debug an incorrect argument replace $27$ by $25 = 5^2$ and notice what goes wrong when you apply the same argument.
– Bill Dubuque
Nov 22 at 18:51
To debug an incorrect argument replace $27$ by $25 = 5^2$ and notice what goes wrong when you apply the same argument.
– Bill Dubuque
Nov 22 at 18:51
add a comment |
2 Answers
2
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up vote
0
down vote
Note that for $(a,b)=(0,-1)$ we have
$$5^{a-b}cdot27^{-(a+b)}=5^1cdot27^1,$$
and $a^2-b^2=-1$, and that for $(a,b)=left(frac{log(5^1cdot27^1)}{log(5/27)},0right)$ we have
$$5^{a-b}cdot27^{-(a+b)}=5^acdot27^{-a}=left(frac{5}{27}right)^{frac{log(5^1cdot27^1)}{log(5/27)}}=5^1cdot27^1,$$
and $a^2-b^2=left(frac{log(5^1cdot27^1)}{log(5/27)}right)^2geq0$. So the value of $a^2-b^2$ is not uniquely determined by the given equation. In particular, this shows that the step you took is not valid.
add a comment |
up vote
-2
down vote
In the above equation a and b are not whole numbers but real numbers
$a-b=1$
$a+b=-1$
We know that
$a^2-b^2=(a+b)(a-b)$
$a^2-b^2=(-1)(1)$
$a^2-b^2=-1$
4
This is incorrect, see my comment.
– Anurag A
Nov 22 at 18:43
This is correct answer you r right about powers but still
– Noone Noone
Nov 22 at 18:46
1
This answer is incorrect - see the comments on the question.
– Bill Dubuque
Nov 22 at 18:54
add a comment |
Your Answer
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2 Answers
2
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2 Answers
2
active
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up vote
0
down vote
Note that for $(a,b)=(0,-1)$ we have
$$5^{a-b}cdot27^{-(a+b)}=5^1cdot27^1,$$
and $a^2-b^2=-1$, and that for $(a,b)=left(frac{log(5^1cdot27^1)}{log(5/27)},0right)$ we have
$$5^{a-b}cdot27^{-(a+b)}=5^acdot27^{-a}=left(frac{5}{27}right)^{frac{log(5^1cdot27^1)}{log(5/27)}}=5^1cdot27^1,$$
and $a^2-b^2=left(frac{log(5^1cdot27^1)}{log(5/27)}right)^2geq0$. So the value of $a^2-b^2$ is not uniquely determined by the given equation. In particular, this shows that the step you took is not valid.
add a comment |
up vote
0
down vote
Note that for $(a,b)=(0,-1)$ we have
$$5^{a-b}cdot27^{-(a+b)}=5^1cdot27^1,$$
and $a^2-b^2=-1$, and that for $(a,b)=left(frac{log(5^1cdot27^1)}{log(5/27)},0right)$ we have
$$5^{a-b}cdot27^{-(a+b)}=5^acdot27^{-a}=left(frac{5}{27}right)^{frac{log(5^1cdot27^1)}{log(5/27)}}=5^1cdot27^1,$$
and $a^2-b^2=left(frac{log(5^1cdot27^1)}{log(5/27)}right)^2geq0$. So the value of $a^2-b^2$ is not uniquely determined by the given equation. In particular, this shows that the step you took is not valid.
add a comment |
up vote
0
down vote
up vote
0
down vote
Note that for $(a,b)=(0,-1)$ we have
$$5^{a-b}cdot27^{-(a+b)}=5^1cdot27^1,$$
and $a^2-b^2=-1$, and that for $(a,b)=left(frac{log(5^1cdot27^1)}{log(5/27)},0right)$ we have
$$5^{a-b}cdot27^{-(a+b)}=5^acdot27^{-a}=left(frac{5}{27}right)^{frac{log(5^1cdot27^1)}{log(5/27)}}=5^1cdot27^1,$$
and $a^2-b^2=left(frac{log(5^1cdot27^1)}{log(5/27)}right)^2geq0$. So the value of $a^2-b^2$ is not uniquely determined by the given equation. In particular, this shows that the step you took is not valid.
Note that for $(a,b)=(0,-1)$ we have
$$5^{a-b}cdot27^{-(a+b)}=5^1cdot27^1,$$
and $a^2-b^2=-1$, and that for $(a,b)=left(frac{log(5^1cdot27^1)}{log(5/27)},0right)$ we have
$$5^{a-b}cdot27^{-(a+b)}=5^acdot27^{-a}=left(frac{5}{27}right)^{frac{log(5^1cdot27^1)}{log(5/27)}}=5^1cdot27^1,$$
and $a^2-b^2=left(frac{log(5^1cdot27^1)}{log(5/27)}right)^2geq0$. So the value of $a^2-b^2$ is not uniquely determined by the given equation. In particular, this shows that the step you took is not valid.
answered Nov 22 at 20:33
Servaes
22.2k33793
22.2k33793
add a comment |
add a comment |
up vote
-2
down vote
In the above equation a and b are not whole numbers but real numbers
$a-b=1$
$a+b=-1$
We know that
$a^2-b^2=(a+b)(a-b)$
$a^2-b^2=(-1)(1)$
$a^2-b^2=-1$
4
This is incorrect, see my comment.
– Anurag A
Nov 22 at 18:43
This is correct answer you r right about powers but still
– Noone Noone
Nov 22 at 18:46
1
This answer is incorrect - see the comments on the question.
– Bill Dubuque
Nov 22 at 18:54
add a comment |
up vote
-2
down vote
In the above equation a and b are not whole numbers but real numbers
$a-b=1$
$a+b=-1$
We know that
$a^2-b^2=(a+b)(a-b)$
$a^2-b^2=(-1)(1)$
$a^2-b^2=-1$
4
This is incorrect, see my comment.
– Anurag A
Nov 22 at 18:43
This is correct answer you r right about powers but still
– Noone Noone
Nov 22 at 18:46
1
This answer is incorrect - see the comments on the question.
– Bill Dubuque
Nov 22 at 18:54
add a comment |
up vote
-2
down vote
up vote
-2
down vote
In the above equation a and b are not whole numbers but real numbers
$a-b=1$
$a+b=-1$
We know that
$a^2-b^2=(a+b)(a-b)$
$a^2-b^2=(-1)(1)$
$a^2-b^2=-1$
In the above equation a and b are not whole numbers but real numbers
$a-b=1$
$a+b=-1$
We know that
$a^2-b^2=(a+b)(a-b)$
$a^2-b^2=(-1)(1)$
$a^2-b^2=-1$
answered Nov 22 at 18:43
Noone Noone
11
11
4
This is incorrect, see my comment.
– Anurag A
Nov 22 at 18:43
This is correct answer you r right about powers but still
– Noone Noone
Nov 22 at 18:46
1
This answer is incorrect - see the comments on the question.
– Bill Dubuque
Nov 22 at 18:54
add a comment |
4
This is incorrect, see my comment.
– Anurag A
Nov 22 at 18:43
This is correct answer you r right about powers but still
– Noone Noone
Nov 22 at 18:46
1
This answer is incorrect - see the comments on the question.
– Bill Dubuque
Nov 22 at 18:54
4
4
This is incorrect, see my comment.
– Anurag A
Nov 22 at 18:43
This is incorrect, see my comment.
– Anurag A
Nov 22 at 18:43
This is correct answer you r right about powers but still
– Noone Noone
Nov 22 at 18:46
This is correct answer you r right about powers but still
– Noone Noone
Nov 22 at 18:46
1
1
This answer is incorrect - see the comments on the question.
– Bill Dubuque
Nov 22 at 18:54
This answer is incorrect - see the comments on the question.
– Bill Dubuque
Nov 22 at 18:54
add a comment |
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2
You are right, you cannot do that step since $a$ and $b$ are real numbers.
– Anurag A
Nov 22 at 18:41
3
@idea that’s not true. $5^x=7$ has a solution $x=log_57$.
– Anurag A
Nov 22 at 18:43
1
To debug an incorrect argument replace $27$ by $25 = 5^2$ and notice what goes wrong when you apply the same argument.
– Bill Dubuque
Nov 22 at 18:51