Maths, Addmaths and Statistics: Post your doubts here!

student8

student8

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plz explain this question to me
The function y = 5x2 - 4x + 12. Write down its derivative and show that when x = 6, a small increase in x of p% causes an increase in y of approximately 2p%.
 
Suchal Riaz

Suchal Riaz

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student8 said:
plz explain this question to me
The function y = 5x2 - 4x + 12. Write down its derivative and show that when x = 6, a small increase in x of p% causes an increase in y of approximately 2p%.
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sorry for being late and for my extremely bad handwriting but it is difficult to write on trackpad. the steps are pretty self explanatory but if u need further explanation tell me. the solution is in the image attached.
 

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mohdumar

mohdumar

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Hamza Hameed Khan said:
Help needed on these questions of trigonometry..!
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sin QRS = sin (180-QRS) = sin QRP
So sin QRP = 3/8

NOW USE SINE RULE

sin QRP = sin PQR
7 = 4

so sin PQR = 3/8*4/7 = 12/56 = 3/14

in 2nd part just use COSINE RULE - dont take cose inverse in the end

4290.gif
 
Haris Bin Zahid

Haris Bin Zahid

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CoolBreeze said:
Can anyone check my solution???
View attachment 21153
Click to expand...
That's wrong: you've made an error in expansion of (-4-2p)^2. It should be 16 + 16p +4p^2.
Secondly, when the question asks you to prove something, you have to show that whatever is stated in the question is true. You simply started off with a '>=' right away-which is undoubtedly an improper approach.
You have to work out the discriminant, which will be 4 . Then, you need to state that since the discriminant is a positive constant, the equation has real roots for all real values of p.
 
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