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2007-06-05 22:24:29 · 8 answers · asked by nivik 3 in Science & Mathematics Mathematics

btw, the answer is x=2

2007-06-05 22:33:24 · update #1

8 answers

2^x+3^x=13
since 2 & 3 r +ve
let x be an integer
2^x<=13 & 3^x<=13
so 2^x<=8 & 3^x<=9
so x<=3 & x<=2
so x<=2
also let x be real & non integer
then .......... i m sorry

2007-06-05 22:59:27 · answer #1 · answered by ? 4 · 0 0

you can show that 2^x + 3^x is increasing monotnolically

because larger x larger 2^x and lager 3^x

once you put x = 0 LHS = 2
x =1 LHS = 5
x =2 LHS = 13
so x = 2 is a solution and there is no other
'
but had 2^x + 3^x = 12 then x >1 and <2 and one could use some approximation formula

2007-06-05 22:42:39 · answer #2 · answered by Mein Hoon Na 7 · 3 0

You have yet to prove that this is the only solution
Take
y=2^x+3^x-13
lim y x=>-infinity is -13
lim y x=> + infinity = + infinity
y´= 2^x*ln2 +3^xln3 always>0
so y is increasing from -13 to + infinity and has only one root
By trail you´ll find x=2

2007-06-06 09:00:55 · answer #3 · answered by santmann2002 7 · 0 0

Brittany, utilising the "distributive property" you first start up on the parentheses and multiply 4 * 2x and then 4* -3. You get: 8x - 12 = 3x +13 you progression the integers to a minimum of one facet by utilising including 12 to the two factors: 8x - 12 + 12 = 3x + 13 + 12 which provides: 8x = 3x + 25 then you definately progression the x's to a minimum of one facet: 8x - 3x = 3x - 3x + 25 5x = 25 then you definately get the x by utilising itself by utilising dividing the two factors by utilising 5: 5x/5 = 25/5 x = 5 Get it?

2017-01-10 15:48:22 · answer #4 · answered by ? 3 · 0 0

2^x + 3^x = 9 + 4

2^x + 3^x = 2^2 + 3^2

x = 2

2007-06-05 22:34:36 · answer #5 · answered by Hell's Angel 3 · 0 2

I stopped using math long ago. You really don't need it with calculators and all. And if I don't have one I always look around for someone to give me the answer. I bet you still think that Latin and French is still spoken.
Dude, you got to party more and relax

2007-06-05 22:29:08 · answer #6 · answered by Anonymous · 0 4

Take lg on both sides of the equation,
xlg2+xlg3=lg13
x(lg2+lg3) = lg13
x(lg6) = lg13
x = (lg13)/(lg6) = 1.43

2007-06-05 22:30:31 · answer #7 · answered by Trina C 2 · 0 5

http://www.mathworld.wolfram.com

2007-06-05 22:26:51 · answer #8 · answered by Anonymous · 0 0

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