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#1 2009-06-07 22:08:31

Dharshi
Member
Registered: 2006-10-31
Posts: 56

Maths

If f (g(x)) =6,where f(x) =2x+3 and g(x) = 3x-4, thenx, to the nearest tenths is equal to______
the answer given is 1.5

Can anyone help me with this?

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#2 2009-06-07 22:16:09

mathsyperson
Moderator
Registered: 2005-06-22
Posts: 4,900

Re: Maths

I get a different answer.
Replacing the functions in the equation with their definitions:

f(3x-4) = 6
2(3x-4) +3 = 6
6x-5 = 6
x = 11/6 ≈ 1.8

Alternatively, you could solve 2(g(x))+3 = 6 for g(x), then use that in g(x) = 3x-4 to get x.
Either way, 1.8 is the answer.


Why did the vector cross the road?
It wanted to be normal.

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