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# P2 functions help watch

1. The function f is given by:

1/(x^2 - 1) where x > 1

a) Find the range of f

The function g is given by:

2/x where x >0

b) Solve gf(x) = 70

I need help on these two questions. How would you go about doing these?
2. (Original post by Jubba)
The function f is given by:

1/(x^2 - 1) where x > 1

a) Find the range of f

The function g is given by:

2/x where x >0

b) Solve gf(x) = 70

I need help on these two questions. How would you go about doing these?
The range of f is all possible values that f(x) can take. So in this case f(x) > 0.

gf(x) = 2/(1/x^2-1) = 2(x^2-1)

Set gf(x) = 70,
70 = 2(x^2-1)
35 = x^2-1
34 = x^2
x = sqrt 34
3. (Original post by ZJuwelH)
The range of f is all possible values that f(x) can take. So in this case f(x) > 0.

gf(x) = 2/(1/x^2-1) = 2(x^2-1)

Set gf(x) = 70,
70 = 2(x^2-1)
35 = x^2-1
34 = x^2
x = sqrt 34
Small mistake: from the line 35 = x^2 - 1

it should then be x^2 = 36, rather than 34
4. (Original post by Silly Sally)
Small mistake: from the line 35 = x^2 - 1

it should then be x^2 = 36, rather than 34
D'oh! Cheers.
5. safe people. nice one.

ZJuwelH i noticed ur located in bethnal green. i liv dere 2. which skool did u go 2?

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