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exponential

Hey

e22x=2ex e^{2-2x} = 2e^{-x}

is this correct:

lne22x=ln2ex[br](22x)(lne)=x(ln2e)[br](22x)=x(lne)+(ln2)[br]22x=x+ln2[br]2x=x+ln22[br]2x=xln2+2[br]x=2ln2 lne^{2-2x} = ln2e^{-x}[br](2-2x)(lne) = -x(ln2e)[br](2-2x) = -x(lne)+(ln2)[br]2-2x = -x + ln2[br]-2x = -x + ln2 -2[br]2x = x - ln2 + 2[br]x = 2 - ln2
(edited 13 years ago)
Reply 1
Nope. Your error is going from ln(2ex)\ln (2e^{-x}) to xln(2e)-x \ln (2e). Notice that xln(2e)=ln(2e)x=ln(2xex)-x\ln (2e) = \ln (2e)^{-x} = \ln (2^{-x}e^{-x}), and not ln(2ex)\ln (2e^{-x}).
Reply 2
Original post by nuodai
Nope. Your error is going from ln(2ex)\ln (2e^{-x}) to xln(2e)-x \ln (2e). Notice that xln(2e)=ln(2e)x=ln(2xex)-x\ln (2e) = \ln (2e)^{-x} = \ln (2^{-x}e^{-x}), and not ln(2ex)\ln (2e^{-x}).


Thank! how about now
lne22x=ln2ex[br](22x)(lne)=(ln2)+(lnex)[br](22x)=(ln2)+(x)(lne)[br]22x=ln2x[br]2x=ln2x2[br]2x=ln2+x+2[br]x=ln2+2 lne^{2-2x} = ln2e^{-x}[br](2-2x)(lne) = (ln2) + (lne^-x)[br](2-2x) = (ln2) + (-x)(lne)[br]2-2x = ln2 - x[br]-2x = ln2 - x - 2[br]2x = -ln2 + x +2[br]x = -ln2 + 2
(edited 13 years ago)
Original post by Limoncello
Thank! how about now
lne22x=ln2ex[br](22x)(lne)=(ln2)+(lnex)[br](22x)=(ln2)+(x)(lne)[br]22x=ln2x[br]2x=ln2x2[br]2x=ln2+x+2[br]x=ln2+2 lne^{2-2x} = ln2e^{-x}[br](2-2x)(lne) = (ln2) + (lne^-x)[br](2-2x) = (ln2) + (-x)(lne)[br]2-2x = ln2 - x[br]-2x = ln2 - x - 2[br]2x = -ln2 + x +2[br]x = -ln2 + 2

That's right.
Reply 4
Original post by Limoncello
Thank! how about now
lne22x=ln2ex[br](22x)(lne)=(ln2)+(lnex)[br](22x)=(ln2)+(x)(lne)[br]22x=ln2x[br]2x=ln2x2[br]2x=ln2+x+2[br]x=ln2+2 lne^{2-2x} = ln2e^{-x}[br](2-2x)(lne) = (ln2) + (lne^-x)[br](2-2x) = (ln2) + (-x)(lne)[br]2-2x = ln2 - x[br]-2x = ln2 - x - 2[br]2x = -ln2 + x +2[br]x = -ln2 + 2


That's right :smile: In questions like this you can check your answer by substituting it into both sides of the given equation to see if they're equal.
Reply 5
Original post by Farhan.Hanif93
That's right.


Thanks :smile:

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