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IGCSE MATHS Doubts

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haris94:

--- Quote from: A@di on May 11, 2010, 04:08:31 pm ---ans 9) (x+2)2 = x2 + 4x + 4.

x2 + 4x + 4 -12 = x2 + 4x - 8

thus, (x+2)2 - 12

--- End quote ---

Thanks
i got it atlast

haris94:
7 f(x) = 10x.
(a) Calculate f(0.5).

(b) Write down the value of f -1(1).

i dont get the "b" part
how do u find the inverse of 10x  ???

Ghost Of Highbury:

--- Quote from: haris94 on May 11, 2010, 04:28:45 pm ---7 f(x) = 10x.
(a) Calculate f(0.5).

(b) Write down the value of f -1(1).

i dont get the "b" part
how do u find the inverse of 10x  ???

--- End quote ---

y = 10x

x = 10^y

log x = y

f(-1) x = log x

f^(-1) 1 = log 1 = 0

longer method..

which paper is this from?

Ghost Of Highbury:
if u havent learnt log. try this method

f-1(1) means, for what value of x in 10x will u get 1

answer = 0

for e.g f(x) = x+2

          f-1x = x-2

f(2) = 4

put 4 in f-1x and u shud get 2

4 -2 = 2

see?

simple.

ksitna:
so like whenever we have f-1 the number in brackets should be the total?

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