Maths help

Alevelhelp.1

15

Help I don’t get this question
How do I do this?

The correct answer is 17

And this question
How do I do this ??

question 4
I know dec func is when the derivative is less than 0 but I got ln0 which comes up with error

(edited 11 months ago)

Reply 1

davros

16

Original post by Alevelhelp.1

Help I don’t get this question
How do I do this?

The correct answer is 17

And this question
How do I do this ??

question 4
I know dec func is when the derivative is less than 0 but I got ln0 which comes up with error

For the 1st one just use that integration is linear i.e. int(f + g) = int f + int g. In this case you know what int f(x) is with those limits, so you're just adding on the integral of '1' between 0 and 10.

For the second your criterion is correct but there shouldn't be any logarithms in your answers - they should all be of the form ke^x or ke^(-x) for some constant k :smile:

Reply 2

Alevelhelp.1

OP

15

Original post by davros

For the 1st one just use that integration is linear i.e. int(f + g) = int f + int g. In this case you know what int f(x) is with those limits, so you're just adding on the integral of '1' between 0 and 10.

For the second your criterion is correct but there shouldn't be any logarithms in your answers - they should all be of the form ke^x or ke^(-x) for some constant k :smile:

Could u plz elaborate on both qs I’m so stuck or can u send me a
workked solution plz
Also the one underneath it Q 5 the correct answer is the last box secx but I don’t get it plz help

(edited 11 months ago)

Reply 3

davros

16

Original post by Alevelhelp.1

Could u plz elaborate on both qs I’m so stuck or can u send me a
workked solution plz

you should know by now we don't do worked solutions here :smile:

and I'm a bit pressed for time right now. for 1st one you know what the integral of '1' is between 0 and 10 - it's just a rectangle of height 1 and width 10, so ...

for the second one you're only using the derivative of e^(ax) = ae^(ax) so just apply that in each case and remember that e^(something) is always positive if "something" is real. You shouldn't get any logarithms in any of the derivatives - refer to your formula sheet/book if unsure :smile:

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