Madman11
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Hi, this question on an exam paper really threw me. I’ve seen a question like occur once before and I was stuck on that too. Is there a set way to doing these types of questions ?
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Also, that was my working for the Question, but in the markscheme, they got a(x+b/2a) .... and so the thing they got outside the bracket was also different. Not sure where they got that 2 from ? As when u divide through by a, you get b/a, not b/2a.
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sanadtw3
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(Original post by Madman11)
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Hi, this question on an exam paper really threw me. I’ve seen a question like occur once before and I was stuck on that too. Is there a set way to doing these types of questions ?
Name:  EEB02CE1-4DD2-4020-8B81-A0C2EC06713C.jpg.jpeg
Views: 9
Size:  25.5 KB

Also, that was my working for the Question, but in the markscheme, they got a(x+b/2a) .... and so the thing they got outside the bracket was also different. Not sure where they got that 2 from ? As when u divide through by a, you get b/a, not b/2a.
are the answers

a= -2
b= 12
c= -13

if so what you had to do is form 3 simultaneous equations.

1st - sub the point (3,5) in to the equation of the curve

2nd - sub the point (5,-3) in to the equation of the curve

3rd - differentiate the equations of the curve and sub in 3. Let the differentiated form of the equations = 0 as it at its maximum at that point.

Solve the 3 equations
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sanadtw3
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(Original post by sanadtw3)
are the answers

a= -2
b= 12
c= -13

if so what you had to do is form 3 simultaneous equations.

1st - sub the point (3,5) in to the equation of the curve

2nd - sub the point (5,-3) in to the equation of the curve

3rd - differentiate the equations of the curve and sub in 3. Let the differentiated form of the equations = 0 as it at its maximum at that point.

Solve the 3 equations
like this
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Madman11
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Ohhh, thanks a lot mate. Is that what you’d recommend to do all the time with these sorta questions - sub in the points you know and, if it gives a maximum, differentiate and solve for 0, then rearrange and solve the equations to get the Unknown’s ?
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sanadtw3
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(Original post by Madman11)
Ohhh, thanks a lot mate. Is that what you’d recommend to do all the time with these sorta questions - sub in the points you know and, if it gives a maximum, differentiate and solve for 0, then rearrange and solve the equations to get the Unknown’s ?
yeah that’s what i’d do personally. It’s what makes most sense to me
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Madman11
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Also, anyone know how to do this question ? Cba making a new thread ahah
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tande33
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Are you familiar with the change base formula? If so that will be useful here!


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Let log k (7) = n (where n is just some number!). Therefore 7 = k^n Take Ln of both sides, and Ln (7) = n Ln (k)

So n = Ln (7) / Ln (k) and you can do the rest ! Hope that helps.
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Madman11
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Ah ok, thanks, I’ll keep that in mind.
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