1999 HSC paper (1 Viewer)

[Arithela]

http://www.boardofstudies.nsw.edu.au/hsc_exams/hsc2000exams/hsc00_maths/99MATH23.PDF

Can someone explain how to get the answers in questions

4Ciii (i only got y<=0 and dont know how to get the other)
8C

 

[avgust90]

http://www.boardofstudies.nsw.edu.au/hsc_exams/hsc2000exams/hsc00_maths/99MATH23.PDF

Can someone explain how to get the answers in questions

4Ciii (i only got y<=0 and dont know how to get the other)
8C

hei arithela...

4ciii) is y>=0 and y<=4x-x^2

8c) is at x=5, f'(x)=0
and f'(5-e)<0
and f'(5+e)>0
Therefore, a local minmum at x=5



Hope dat helps =]

 

[munchiecrunchie]

for 4ciii, the shaded region is also bound by the parabola. So you would test a point that satisfies that region into an inequality (eg y>= 4x - x^2) - if the point satisfies, then its the correct inequality, if it doesn't, then its the opposing inequality.

8C - x = 5. on either side of a minimum, the gradient changes from negative to positive. stationary points when the gradient function is zero, therefore x=5 is the local minimum

 

[Arithela]

thank you