# Edexcel c1 may 2006 mark scheme error? Watch

1. this error involves question 10c). dy/dx=2x+3/x^2

therefore dy/dx=2x+3(x^-2)
x(-2)=(2*-2)+(3*(-2^-2))
=-4+(3*-1/4)
=-4-3/4
=-4.75

so the gradient when x=-2 is -4.75.....the mark scheme states it is -3.25. this value can be made by -4 + 0.75 but clearly u have to minus 0.75??? :/
2. (Original post by Rahul.S)
this error involves question 10c). dy/dx=2x+3/x^2

therefore dy/dx=2x+3(x^-2)
x(-2)=(2*-2)+(3*(-2^-2))
=-4+(3*-1/4)
=-4-3/4
=-4.75

so the gradient when x=-2 is -4.75.....the mark scheme states it is -3.25. this value can be made by -4 + 0.75 but clearly u have to minus 0.75??? :/
dy/dx 3/x^2 -> dy/dx 3(x^-2) = -6x^-3 -> -6/x^3
x=-2 -> -6/-8 -> +3/4
3. (Original post by uninspirational)
dy/dx 3/x^2 -> dy/dx 3(x^-2) = -6x^-3 -> -6/x^3
x=-2 -> -6/-8 -> +3/4
lol dw ur showin the alternate route....i understand wt i did wrong using my way cheers duo!
4. (Original post by Rahul.S)
this error involves question 10c). dy/dx=2x+3/x^2

therefore dy/dx=2x+3(x^-2)
x(-2)=(2*-2)+(3*(-2^-2))
=-4+(3*-1/4)
=-4-3/4
=-4.75

so the gradient when x=-2 is -4.75.....the mark scheme states it is -3.25. this value can be made by -4 + 0.75 but clearly u have to minus 0.75??? :/
Whats -2 x -2 ???? +4 not -4
5. (Original post by Beansontoast yum)
Whats -2 x -2 ???? +4 not -4
yh thts the part i got wrong....its +4 cuz the minus cancel each other out

RIP C1

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