How many positive real numbers are there such that x x x = ( x x ) x
EDIT
Details and Assumptions - You can't raise 0 to the power 0. So, 0 is not a solution
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Log(1) = 0. x can not be equal to 0. So two solutions . 1 and 9/4.
Zero is not a solution as zero
can't
be raised to power zero.
Also,
l
o
g
(
1
)
=
0
So, two solutions are
1
and
9
/
4
and not
9
/
4
and
0
exactly the same!!
Expand the right-hand side to get
x x x = x x × x x
We are told that x is not 0,
x x = x x
First take log on both sides...then on squaring we get x^3=9x^2/4... We can easily do the question by plotting curves between y=x^3 and y=9x^2/4 hence we will get 3 points of intersection out of which zero is not in the domain . hence only two possible solutions
x
x
∗
x
=
x
x
3
/
2
(
x
∗
x
)
x
=
(
x
x
∗
x
x
/
2
)
=
x
(
3
/
2
)
x
∴
x
=
1
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d
e
x
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a
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b
a
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.
.
.
.
.
x
3
/
2
=
(
3
/
2
)
x
∴
x
(
x
−
3
/
2
)
=
0
.
.
.
.
.
.
i
f
x
=
0
.
x can not be equal to 0. 0 can not be raised to any power.
So two numbers are 1 and 9/4.
(Please note, I have made correction.)
what about "1"? it is also a +v e real number and satisfies the equation.
Log in to reply
Thanks. You are right. I have made correction.
1 for log x 9/4 for( x^1/2)-3/2
Take log of both sides to reduce the equation to :
x * Sqrt(x) log(x)=(3/2) log(x)
Thus, x * Sqrt(x)=(3/2), which implies Square root of x= 3/2 .
This gives x=9/4 which is one possible solution and the other one is 1.
2 solutions .. because you can substitute the x by 1 or 0
not 0, but 4
You can't raise 0 to the power 0.
You get one solution as 9/4 and other as 1. 0^0 is indeterminate
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x x l o g x = 2 3 x l o g x
x l o g x ( x − 2 3 ) = 0
x can't be zero , thus 2 solutions