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avatar+1904 

Solve for x.  Please show how you got to your answer.

 

\(\frac{{2x}^{2}}{\sqrt{{x}^{4}}}+2=\frac{5}{\sqrt{{3}^{x}}}\)

 Jun 8, 2016
edited by gibsonj338  Jun 8, 2016

Best Answer 

 #1
avatar+23252 
+10

Solve:    2x2 / sqrt( x)  +  2   =   5 / sqrt( 3x )

 

Since  sqrt( x)  =  x2     --->    2x2 / sqrt( x)     --->     2x2 / x2     --->     2

 

Therefore:    2x2 / sqrt( x)  +  2   =  2 + 2  =  4

 

The problem reduces to:     4  =  5 / sqrt( 3x )

 

Multiply both sides by  sqrt( 3x )  to get  4·sqrt( 3x )  =   5

 

Square both sides:        16 · 3x  =  25

--->                                       3x  =  25 / 16

 

Find the log of both sides:      log( 3x )  =  log( 25 / 16)

--->                                       x · log( 3)  =  log( 25 / 16 )

--->                                                    x  =  log( 25 / 16) / log( 3 )

--->                                                    x  =  0,406228   (approximately)

 Jun 9, 2016
 #1
avatar+23252 
+10
Best Answer

Solve:    2x2 / sqrt( x)  +  2   =   5 / sqrt( 3x )

 

Since  sqrt( x)  =  x2     --->    2x2 / sqrt( x)     --->     2x2 / x2     --->     2

 

Therefore:    2x2 / sqrt( x)  +  2   =  2 + 2  =  4

 

The problem reduces to:     4  =  5 / sqrt( 3x )

 

Multiply both sides by  sqrt( 3x )  to get  4·sqrt( 3x )  =   5

 

Square both sides:        16 · 3x  =  25

--->                                       3x  =  25 / 16

 

Find the log of both sides:      log( 3x )  =  log( 25 / 16)

--->                                       x · log( 3)  =  log( 25 / 16 )

--->                                                    x  =  log( 25 / 16) / log( 3 )

--->                                                    x  =  0,406228   (approximately)

geno3141 Jun 9, 2016
 #2
avatar+1904 
0

After you find a possible solution, it would be a good idea to plug the possible solution into the origional equation to see if the possible solution is a solution which I will do now.

 

\(\frac{{2(0.406228)}^{2}}{\sqrt{{0.406228}^{4}}}+2=\frac{5}{\sqrt{{3}^{0.406228}}}\)

 

\(\frac{2(0.165021187984)}{\sqrt{{0.406228}^{4}}}+2=\frac{5}{\sqrt{{3}^{0.406228}}}\)

 

\(\frac{0.330042375968}{\sqrt{{0.406228}^{4}}}+2=\frac{5}{\sqrt{{3}^{0.406228}}}\)

 

\(\frac{0.330042375968}{\sqrt{0.0272319924836507}}+2=\frac{5}{\sqrt{{3}^{0.406228}}}\)

 

\(\frac{0.330042375968}{0.1650211879840001031}+2=\frac{5}{\sqrt{{3}^{0.406228}}}\)

 

\(1.9999999999999987504635 +2=\frac{5}{\sqrt{{3}^{0.406228}}}\)

 

\(3.9999999999999987504635 =\frac{5}{\sqrt{{3}^{0.406228}}}\)

 

\(3.9999999999999987504635 =\frac{5}{\sqrt{1.5624999533947653}}\)

 

\(3.9999999999999987504635 =\frac{5}{1.249999981357905981}\)

 

\(3.9999999999999987504635 = 4.000000059654701750471\)

 

\(3.9999999999999987504635 ≠ 4.000000059654701750471\)

 

Because only one possible solution was found and it turned out not to be a solution, there is no solution.

gibsonj338  Jun 9, 2016
 #3
avatar+33661 
0

Clearly there is a solution!

 

sol

geno gave both an exact and an approximate result.  The fact that the approximate solution doesn't match the original equation exactly is hardly surprising!

 Jun 9, 2016

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