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Mathematics 17 Online
OpenStudy (yamyam70):

how would I solve for x ? ( see message )

OpenStudy (yamyam70):

3^ sqrt x +4 = 27 ^sqrt x

OpenStudy (yamyam70):

the exponent of the LHS is

OpenStudy (yamyam70):

\[\sqrt{x} + 4\]

OpenStudy (unklerhaukus):

so what do you get when you change the base of the RHS

OpenStudy (yamyam70):

(3)^3(sqrtx)

OpenStudy (unklerhaukus):

yep, so now the bases on LHS and RHS are the same \[\large3^{\sqrt x +4} = 3^{3\sqrt x} \] taking the log to base three on both sides \[\large\log_33^{\sqrt x +4} = \log_33^{3\sqrt x} \] cancles the bases \[\large{\sqrt x +4} = {3\sqrt x} \]

OpenStudy (unklerhaukus):

now just solve for \(x\)

OpenStudy (yamyam70):

thats the problem unkle, from that equation is it legal for this to happen \[(\sqrt{x} + 4)^2 = (3\sqrt{x})^2\]

OpenStudy (unklerhaukus):

hmm, there is a much eaisier way

OpenStudy (yamyam70):

Please :)

OpenStudy (unklerhaukus):

** √x+4 = 3√x take away √x form both sides

OpenStudy (yamyam70):

\[\sqrt{x} + 4 = 3\sqrt{x} / \sqrt{x } ??\]

OpenStudy (unklerhaukus):

√x+4 -√x = 3√x -√x 4 = (3-1)√x

OpenStudy (unklerhaukus):

{the four wasent undrer the square root was it?}

OpenStudy (yamyam70):

yep

OpenStudy (unklerhaukus):

it was? or it wasn't?

OpenStudy (yamyam70):

it was not under the sqrt

OpenStudy (unklerhaukus):

ok good.

OpenStudy (yamyam70):

I'm a little confused about the RHS

OpenStudy (yamyam70):

oh you factored it ?

OpenStudy (unklerhaukus):

we had 3√x -√x right? in other terms 3 B - B to simplify you have to realize that the terms are common (3-1)B we can combine the coefficients and simplify ..B

OpenStudy (yamyam70):

\[(4 )^2= (2\sqrt{x})^2\]

OpenStudy (yamyam70):

16 = 4x x = 4 is it correct ?

OpenStudy (unklerhaukus):

yeah x works out to equal 4

OpenStudy (yamyam70):

Thanks again unckle ! I shall do the checking :)

OpenStudy (unklerhaukus):

but you dont have to square the expression intill tha last step 4 = (3-1)√x 4 = 2√x 2 = √x 4 = x

OpenStudy (yamyam70):

Thanks for the tip :))

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