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C3 Maths: Simplifying exponential question - Help

Hi

I have done this q but, when I put the value of x back into the question I get 5.11..(...)

ImageUploadedByStudent Room1476879642.020935.jpg

I'm not sure where I've gone wrong, could someone help me please?

Thanks



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Reply 1
Oh wait. is the answer just ln(2)?


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(e^x +3)(e^x -2)=0
x = ln2
Original post by Yusufff
Oh wait. is the answer just ln(2)?


Posted from TSR Mobile


Yes
Reply 4
Original post by Mr Moon Man
(e^x +3)(e^x -2)=0
x = ln2


Ahh substitution - I forgot about this. I remember now that it can be factorised haha - thanks :smile:


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loool my g. Sick handwriting. And btw you should factorise them cos it's a quadratic
Original post by Yusufff
Hi

I have done this q but, when I put the value of x back into the question I get 5.11..(...)


I'm not sure where I've gone wrong, could someone help me please?

Thanks

Posted from TSR Mobile


You've gone wrong straight after the first line because you do NOT perform the same operation to each individual term of an equation, you learn this at GCSE.

While yours is incorrect, the correct way to write it would be ln(e2x+ex)=ln(6)\ln(e^{2x}+e^x)=\ln(6) and while this form is useless for what we need to do, that is how you'd take logarithms of both sides.

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