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# P3 Differential watch

1. Please can someone explain to me how to solve the following equation:
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2. (Original post by Pixelfairy #1)
Please can someone explain to me how to solve the following equation:
asssuming that k is a constant
just expand the (1-2x)(1-4x) and integrate...
you dont have to add the k
leave it out when integrating
after integrating,put the k back in
3. (Original post by MalaysianDude)
asssuming that k is a constant
just expand the (1-2x)(1-4x) and integrate...
you dont have to add the k
leave it out when integrating
after integrating,put the k back in
Did you notice that the LHS is dy/dt and not dy/dx?

Pixelfairy, is x a function of t? Maybe you can use dy/dx = dy/dt * dt/dx and then integrate the RHS wrt x (not sure though).
4. (Original post by MalaysianDude)
asssuming that k is a constant
just expand the (1-2x)(1-4x) and integrate...
you dont have to add the k
leave it out when integrating
after integrating,put the k back in
lol that makes sense... but I tried to take the xs over to the other side and ended up with 1/the quadratic

Thanks... I'm having a bad P3 day today
5. (Original post by Pixelfairy #1)
Please can someone explain to me how to solve the following equation:

dy/dx = k(1 - 2x)(1 - 4x)

Put all x's onto the right hand side and multiply out brackets.
dy/k = 1 - 6x + 8x^2

Then integrate:
{1/k.dy = {1 - 6x + 8x^2.dx

Answer = 1/k.y = x - 3x^2 + 8x^3/3 + C

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