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Intergration help

So here's the picture of the question and my working out, I tried integrating it and cleaning it up, then put it into y = mx + c and got a ridiculous answer.. can anyones see where i went wrong or if im doing it completely wrong

side ways im sorry

IMG_20141130_122522[1].jpg476.4KB

Reply 1

civeng1597

To find the gradient you're supposed to differentiate, not integrate. Get dy/dx then put in the x value to get the gradient

Reply 2

Mutleybm1996

Original post by civeng1597

To find the gradient you're supposed to differentiate, not integrate. Get dy/dx then put in the x value to get the gradient

S/he was given the gradient

Posted from TSR Mobile

Reply 3

philgreek

Original post by EpicTree

{working}

It all looks good to me except when you calculate c you put 3*9^2 when you actually want 3*9^3.

So you're finally answer for c would be -2334

and your equation y = 3x^3 + 6x^1.5 - 2334

Reply 4

EpicTree

Original post by philgreek

It all looks good to me except when you calculate c you put 3*9^2 when you actually want 3*9^3.

So you're finally answer for c would be -2334

and your equation y = 3x^3 + 6x^1.5 - 2334

oh yea I recalculated it and I got the same, I accidently squared the first one rather than cubing it. But this is all noncalculator so the multiplication is pretty difficult

Reply 5

philgreek

Original post by EpicTree

oh yea I recalculated it and I got the same, I accidently squared the first one rather than cubing it. But this is all noncalculator so the multiplication is pretty difficult

Are you certain it is non-calculator then, as I agree that it isn't the sort of numbers you would expect to deal with in a non-calc questions. Either way the answer definitely works fine so that's something.