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C3 functions?

http://www.examsolutions.net/a-level-maths-papers/Edexcel/Core-Maths/Core-Maths-C3/2009-January/paper.php#Q5
part d is quite a struggle so here's what i've done so far

\frac{d}{dx} [fg(x)]

i did

x^2+3e^{x^2} \Rightarrow 2x+3x^2e^{x^2-1}

set that equal to

x(xe^{x^2} +2)

which gives

2x+3x^2e^{x^2-1}=x(xe^{x^2} +2)

i got rid of 2x from both sides then the x^2

which left me with

3e^{x^2-1}=ex^2

i then did ln of each side which gets me

ln3e^{x^2-1}=lnex^2

i then split it up into 4 separate bits

ln3+lne^{x^2-1}=lne+lnx^2

ln3+(x^2-1)lne=1+2lnx

ln3+(x^2-1)=1+2lnx

and that's as far as i've gotten, not sure what to do from here on.

(edited 7 years ago)

Reply 1

edothero

\dfrac{d}{dx}[3e^{x^{2}}] \not= 3x^2e^{x^2-1}

Spoiler

(edited 7 years ago)

Reply 2

bigdonger

Original post by edothero

\dfrac{d}{dx}[3e^{x^{2}}] \not= 3x^2e^{x^2-1}

Spoiler

Reply 3

thegreatwhale

Original post by edothero

\dfrac{d}{dx}[3e^{x^{2}}] \not= 3x^2e^{x^2-1}

Spoiler

right so it would be

6xe^{x^2}

then?

so i managed to get 6 or 0 as an answer is that it?

(edited 7 years ago)

Reply 4

edothero

Original post by thegreatwhale

right so it would be

6xe^{x^2}

then?

so i managed to get 6 or 0 as an answer is that it?

Sounds good :yy:

Reply 5

thegreatwhale

Original post by edothero

Sounds good :yy:

and that's it nothing else?

Reply 6

edothero

Original post by thegreatwhale

and that's it nothing else?

Yup
x = 0, 6 is correct.

Reply 7

thegreatwhale

Original post by edothero

Yup
x = 0, 6 is correct.

thanks

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