Mathematics
7 Online
OpenStudy (anonymous):
Sollution set of
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OpenStudy (anonymous):
\[\huge \log_x(2+x) \le \log_x(6-x)\]
OpenStudy (anonymous):
Can't we cancel \(\log_x\) both the sides or by taking anti-logarithm?
ganeshie8 (ganeshie8):
As a start : change to natural log base and cancel some stuff maybe
OpenStudy (anonymous):
you don't know base haha
ganeshie8 (ganeshie8):
we cannot cancel something without knowing its sign
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OpenStudy (anonymous):
or , i was thinking of taking two conditions
one which will change sign
one which will not
and take intersection
OpenStudy (anonymous):
Its sign?? What is "its' here??
OpenStudy (anonymous):
you can't just cancel the logs ,
OpenStudy (anonymous):
i wanted to make sure
OpenStudy (anonymous):
that is not giving the anser
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OpenStudy (anonymous):
I am asking Ganesh.. :P
ganeshie8 (ganeshie8):
considering two cases sounds like a nice plan
OpenStudy (anonymous):
the plan failed
ganeshie8 (ganeshie8):
something = base, water :)
OpenStudy (anonymous):
i did it , i am getting
x ge 0
x le 0
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ganeshie8 (ganeshie8):
from the input inequality
x>0
x+2>0
6-x>0
yes ?
OpenStudy (anonymous):
Between -2 and 6..
ganeshie8 (ganeshie8):
that bounds the possible solutions to
\[\large 0\lt x\lt 6\]
ganeshie8 (ganeshie8):
we still need to find out the actual solutions
OpenStudy (anonymous):
yeah answer is
(1.2]
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OpenStudy (anonymous):
Yes you are right..
ganeshie8 (ganeshie8):
when is logx negative ?
OpenStudy (anonymous):
Between 0 and 1??
OpenStudy (anonymous):
yeah
OpenStudy (anonymous):
When x is in decimal form..
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ganeshie8 (ganeshie8):
\[\large \log_x(2+x) \le \log_x(6-x) \]
\[\large \dfrac{\ln (2+x)}{\ln x} \le \dfrac{\ln (6-x) }{\ln x}\]
ganeshie8 (ganeshie8):
so you don't have to flip inequality when you multiply lnx for x>1, yes ?
ganeshie8 (ganeshie8):
case 1 :
0<x<1
case 2:
1<x<6
OpenStudy (anonymous):
yes
OpenStudy (anonymous):
Leave it , i will ask my prof.
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ganeshie8 (ganeshie8):
aren't we done ?
ganeshie8 (ganeshie8):
case 1 :
0<x<1
\[\large 2+x \ge 6-x \implies x \ge 2\]
but we assumed that 0<x<1
so no solutions for case 1
ganeshie8 (ganeshie8):
case 2 :
1<x<6
\[\large 2+x \le 6-x \implies x \le 2\]
\(\large (x\le 2 ) \wedge ( 1\lt x\lt 6) \implies 1\lt x\le 2 \)
OpenStudy (anonymous):
yup , we were done