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Additional Maths (p2)

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divineobsidian:
i think the person above was correct. its

change in x/change in y = dx/dy and you rearrange

Ghost Of Highbury:
rate of change
the rate of change of a variable x with respect to time t is dx/dt

if x and y are related by the equaton y=f(x). then the rate of change dx/dt and dy/dt are related by
dy/dt = dy/dx * dx/dt

if its small change
then
&y/&x = dy/dx

the percentage change in x is &x/x *100

--
hope this helped
 :D

Ghost Of Highbury:
for e.g  (m = pi)
the area of a circle increases at a rate of  2m cm^2/s. Calculate the rate of increase of the radius at radius = 6cm

Ans: dA/dr = dt/dr  * dA/dt
 A= mr^2 therefore dA/dr = 2mr

at r = 6cm 2mr = 12m
so dA/dr = 12m
dA/dt = 2m cm^2/s

so the equation is

12m = dt/dr  *  2m
therefore dt/dr = 12m/2m = 6

dt/dr = 6
therefore dr/dt = 1/6  (inverse)

easy..
hope it helped
thank u

note: m = pi (i cud not put the symbol of pi in the question)
 :)

vanibharutham:
Thanks :D + rep

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