Mathematics: Post your doubts here!

[hellodjfos;s'ff]

Anyone part 3 with solution?

Use trigonometry... draw a triangle AOD(with the perpendicular) and find the length of all sides. You have vectors AO, OD and can find AD. Find the magnitude of these vectors(they will be the lengths of the sides of the triangle). Now find an angle AOD or ADO and use the angle to find the perpendicular's distance using basic trig.
Check my diagram to understand this.

 

[A*****]

No, I know that multiplying a number by i adds pi/2 to its argument and multiplying it by a constant multiplies its length in the argand diagram

Alright and will division do the reverse? And what if it is multiplied by a complex number?

 

[Hamnah Zahoor]

hellodjfos;s'ff Can you please give me a rough idea of what is coding while calculating mean and standard deviation.

 

[hellodjfos;s'ff]

hellodjfos;s'ff Can you please give me a rough idea of what is coding while calculating mean and standard deviation.

Σ(x) would be the sum of all values in a data set. Σ(x-a) would mean that a is subtracted from every value in the data set for example I have a data set of 70 80 90 100... the Σ(x) is 340 but Σ(x-10) would be 10 subtracted from every value. We could manually calculate this but that would be very time-consuming and questions often dont tell us all the values in a data set. So we can use a formula of coding(which is given to us in the formula sheet):
Mean=Σ(x-a)/n +a..... so I'll use the values I used above to prove this ok. The mean of those values is 85, n is 4 and I am trying to find Σ(x-10), so I use this formula.
85=Σ(x-10)/4 +10.... Σ(x-10) turns out to be 300. You can now also try to subtract 10 from each value in the data set and find their sum and you would get the same answer.

The other formula used in coding(also mentioned in formula sheet) is:
Variance=Σ(x-a)^2/n - (Σ(x-a)/n)^2.... this is similar to the formula of finding variance itself. The concept around this can only be understood once you attempt questions.

 

[Ebrahim12]

Alright and will division do the reverse? And what if it is multiplied by a complex number?

Yes division is the opposite, you get these from the arg(az) = arg(z) + arg(z) and Re(az) = Re(a)*Re(z) rules. For complex numbers you have to work it out using these rules I think.

 

[Hamnah Zahoor]

Σ(x) would be the sum of all values in a data set. Σ(x-a) would mean that a is subtracted from every value in the data set for example I have a data set of 70 80 90 100... the Σ(x) is 340 but Σ(x-10) would be 10 subtracted from every value. We could manually calculate this but that would be very time-consuming and questions often dont tell us all the values in a data set. So we can use a formula of coding(which is given to us in the formula sheet):
Mean=Σ(x-a)/n +a..... so I'll use the values I used above to prove this ok. The mean of those values is 85, n is 4 and I am trying to find Σ(x-10), so I use this formula.
85=Σ(x-10)/4 +10.... Σ(x-10) turns out to be 300. You can now also try to subtract 10 from each value in the data set and find their sum and you would get the same answer.

The other formula used in coding(also mentioned in formula sheet) is:
Variance=Σ(x-a)^2/n - (Σ(x-a)/n)^2.... this is similar to the formula of finding variance itself. The concept around this can only be understood once you attempt questions.

Thank you

 

[A*****]

Yes division is the opposite, you get these from the arg(az) = arg(z) + arg(z) and Re(az) = Re(a)*Re(z) rules. For complex numbers you have to work it out using these rules I think.

Thanks man!

 

[MShaheerUddin]

Can anyone tell me:
In mechanics paper, when we integrate an expression, when should we have to find C as well..? In many questions, sometimes it requires c and sometimes it does not.
How can you judge that you have to find C.

 

[Ebrahim12]

Can anyone tell me:
In mechanics paper, when we integrate an expression, when should we have to find C as well..? In many questions, sometimes it requires c and sometimes it does not.
How can you judge that you have to find C.

You always add C when integrating and solve for it, its just that sometimes C equals zero.

 

[A*****]

You always add C when integrating and solve for it, its just that sometimes C equals zero.

And sometimes obviously you've got the limits so c is not needed

 

[Shemyaa]

Did anyone solve P1 paper? Or did you find the ms?
And question: Do Feb/March papers give an idea about May/June session paper? Because the paper was really easy and I don't think that's how it'll go this year.
I think stats will be tricky this year,

 

[Shemyaa]

PURE MATHS 1 FEB/MARCH ANSWERS (MINE)
1) P=6
2) f(x)=2/9x^3-x^2+2
3)118 cm^2
4)dy/dx=-2(2x-1)^-2 +2
d^2y/dx^2=8(2x-1)^-3
5) x=8 in minimum and x=1 is the maximum
6) a) q= 2 or -11/3 b) 130.7
7) b) p=8 and n=42
8) 54.8 and 125.3 b)sq root 3 +tan (2x)
9) a) k=2 b) f inverse is 2- square root (x-3) and domain is f(x) >4 c) gf(x) range is < or equal to 1/3 (I confused the most here tho)
10) 117pi/4 b) (0,78/11)
11)a)8 square root 2, b) T(4,8)
Please share your answers if you solved,

 

[A*****]

PURE MATHS 1 FEB/MARCH ANSWERS (MINE)
1) P=6
2) f(x)=2/9x^3-x^2+2
3)118 cm^2
4)dy/dx=-2(2x-1)^-2 +2
d^2y/dx^2=8(2x-1)^-3
5) x=8 in minimum and x=1 is the maximum
6) a) q= 2 or -11/3 b) 130.7
7) b) p=8 and n=42
8) 54.8 and 125.3 b)sq root 3 +tan (2x)
9) a) k=2 b) f inverse is 2- square root (x-3) and domain is f(x) >4 c) gf(x) range is < or equal to 1/3 (I confused the most here tho)
10) 117pi/4 b) (0,78/11)
11)a)8 square root 2, b) T(4,8)
Please share your answers if you solved,

I'll solve it tomorrow and get back to u!

 

[A*****]

View attachment 64668
I did it this way in 7iii, can you explain how did you get 5880?

First consider the situation if the letter A is in between...MAM would be 1 object and these 3 letters can't switch positions so that would be 7!/2!= 2520
If it's some other letter then there'd be 4 options for the middle letter so no. of arrangements would be 4x 7!/3!= 3360
Adding both gives 5880

 

[Shemyaa]

First consider the situation if the letter A is in between...MAM would be 1 object and these 3 letters can't switch positions so that would be 7!/2!= 2520
If it's some other letter then there'd be 4 options for the middle letter so no. of arrangements would be 4x 7!/3!= 3360
Adding both gives 5880

Thank youu

 

[mittul8yu98]

Does any one have statistics 2 notes
I have even started preparing
please help

 

[Shemyaa]

Does any one have statistics 2 notes
I have even started preparing
please help

I dont take S2 but look into this link
https://www.physicsandmathstutor.com/a-level-maths-papers/

 

[mittul8yu98]

I dont take S2 but look into this link
https://www.physicsandmathstutor.com/a-level-maths-papers/

thanks a lot

 

[student3737]

Hey guys are we supposed to know the large data set for edexcel? It’s a huge list, and our teachers never specified , she would just give us the data set in mocks

 

[Mushraf altaf]

ill appreciate help with this one,