Mathematics Week 4 Question

[Jithesh Gopal]

As per the tutorial solution it does seems correct. 

Alternately if I had worked saying that slope using differentiation  

dl / dt = 2at  +  b    and equate it to the likes as above =

   4 (2t +1 ) / 2   = 4t + 2   

would imply that  a  = 2 and b  = 2 ... 

looks like answer depends on my choice of solution method. Please clarify  this confusion.   

thanks 

Jithesh

Then  I would1got an incorrect answer 

[Debajyoti Biswas]

Can you please specify the question, also slope of parabola is (2ax+b) .Please check with the solution tips and faq and check your calculations also.

[Jithesh Gopal]

Question 8 week 4 

[shyam sundar]

It should not depend on the method chosen for solving the problem. I too worked out in the same way and got a =2 and b=2.

Basically increase in likes from 3 to 4 seconds indicates increase in like per unit increase in time at t, which is slope given by 4 (2t+1)/2. Should be equal to slope of equation,  at^2+bt+c which is 2at +b.

So slope at 3 is 14 so 6a+b=14 and similarly slope at 0 is 2 (4*0.5) so b=2 and a =2.

Please can anyone help to clarify this?

Thanks.