If log_ba=1/x and log_a √b =3x^2logba=1xandlogab=3x2, show that x =1/6?

3 Answers
Jun 3, 2018

"see explanation"see explanation

Explanation:

"using the "color(blue)"law of logarithms"using the law of logarithms

•color(white)(x)log_b x=nhArrx=b^nxlogbx=nx=bn

log_b a=1/xrArra=b^(1/x)logba=1xa=b1x

log_a b^(1/2)=3x^2rArrb^(1/2)=a^(3x^2)logab12=3x2b12=a3x2

"substitute "a=b^(1/x)" into "a^(3x^2)substitute a=b1x into a3x2

b^(1/2)=(b^(1/x))^(3x^2)=b^(3x)b12=(b1x)3x2=b3x

"we have "b^(1/2)=b^(3x)we have b12=b3x

3x=1/23x=12

"divide both sides by 3"divide both sides by 3

x=(1/2)/3=1/6x=123=16

x=1/6x=16

Explanation:

log_b a=1/xlogba=1x

So

xlog_ba=1xlogba=1

x=1/log_b ax=1logba

x=log_abx=logab

Now

1/2log_a b=3x^2" "12logab=3x2 (substituting from log_a b=xlogab=x)

So

x/2=3x^2x2=3x2

x=6x^2x=6x2

6x=16x=1

x=1/6x=16 with x !=0x0

Hence proved.

Jun 3, 2018

We will start the proof

Explanation:

We have
ln(a)/ln(b)=1/xln(a)ln(b)=1x
and

1/2*ln(b)/ln(a)=3x^212ln(b)ln(a)=3x2
so

ln(a)/ln(b)=1/(6x^2)ln(a)ln(b)=16x2

using the first equation we get
1/x=1/(6x^2)1x=16x2

multiplying by x^2x2 we get

x=1/6x=16 for xne 0x0