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OpenStudy (dtan5457):
\[3^x-2(3)^{1-x}=5\]
OpenStudy (dtan5457):
compute 3^(2x+1)
OpenStudy (faiqraees):
can you split 3^1-x in to two exponents?
jhonyy9 (jhonyy9):
great @FaiqRaees - this is the first step sure
OpenStudy (dtan5457):
can multiply 3^(x+1) on every side?
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OpenStudy (faiqraees):
A^m * A^n = A^m+n
OpenStudy (dtan5457):
then I can get 3^(2x+1) on the left side
OpenStudy (faiqraees):
first its not 3^2x+1 its 2(3^1-x) and no. After this you can make the l.h.s a complete exponent of 3
OpenStudy (dtan5457):
ok if i split it i will get 3^1 x 3^-x
OpenStudy (faiqraees):
yes which will be \[3/3^x\]
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OpenStudy (faiqraees):
now multiply the two with the fraction.
OpenStudy (dtan5457):
-6/3^x
OpenStudy (faiqraees):
and when you've done it make an equation y=3^x and then subsitute y in place of 3^x and then you've gotten a quadratic equation. Solve it find values of y and then use them to fund the values of x
OpenStudy (faiqraees):
find*
OpenStudy (dtan5457):
wait when i've done what? do i multiply the whole thing by 3^x now to remove the fraction?
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OpenStudy (faiqraees):
yes
OpenStudy (dtan5457):
now I have 3^(2x)-6=3^(x)(5)
OpenStudy (dtan5457):
do i solve for x and put it back into 3^(2x+1)
OpenStudy (dtan5457):
or do i do that directly from the equation not sure
OpenStudy (dtan5457):
actually i see what you mean by quadratic equation i set 3^x=u
then i get u^2-5u-6=0
i get 6,-1
do i set those 2 numbers to 3^x?
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OpenStudy (faiqraees):
yes
OpenStudy (dtan5457):
so i solve for 3^x=6 and -1?
OpenStudy (faiqraees):
yes
OpenStudy (faiqraees):
btw you have to neglect -1 because no number when squared to any number results in a negative number.
OpenStudy (dtan5457):
how do i solve for x here again lol
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OpenStudy (jdoe0001):
is \(\large\bf 3^x-2(3)^{1-x}=5\) it? just clarifying
OpenStudy (faiqraees):
apply logarithm
OpenStudy (dtan5457):
yes
OpenStudy (faiqraees):
should i walk you through the logarithm part or you know how to apply them
OpenStudy (dtan5457):
i remember the exponential form to log form, this becomes log3(6)=x but i actually forgot how to plug that into calculator
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OpenStudy (jdoe0001):
use the log change of base rule, to make it either ln or base10
OpenStudy (dtan5457):
yeah i got it
OpenStudy (dtan5457):
its just log(6)/log(3)
OpenStudy (jdoe0001):
yeap
OpenStudy (dtan5457):
so answer we get 108
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OpenStudy (jdoe0001):
hmmm log(3)/log(6) gives me something else =|
OpenStudy (faiqraees):
you have to use log 6 /log 3
OpenStudy (faiqraees):
and answer will be 1.630929
OpenStudy (dtan5457):
108 i meant for the problem
OpenStudy (jdoe0001):
ohhhh rats... yeah.. mistead there
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