# Maths help with P2 EdexcelWatch

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#1
Hi
I was wondering how you find the range of a function from its domain. Say it is f:x --> x^2 + 5, xER.?

Also, how do draw graphs like these?:

y = 0.5(4 - e^x) ?

I thought it would be the reflection of e^x in the x=axis and then add 2 in y direction - is this wrong?

Regards

Matt
0
16 years ago
#2
For x^2 + 5 the range of values will be F(x)>= 5 because x^2 is always greater than 0 as such at x = 0 it has a minimum. This can also be done by differentiation dy/dx = 0
So 2x = 0 x = 0

As for your graph, sounds good to me, you will get the right shape woth the method you have suggested. All the best, Dan
0
16 years ago
#3
But, if you expand it, wouldn't it be 2-0.5e^x? So the curve would be shallower i.e. closer to the x-axis, then reflected, and then moved 2 up in the y direction.
Hope the exams ok, and not 2 tough.
Good luck!
0
16 years ago
#4
Very true sir. Hope I don't do that on Friday. I think we learnt to expand brackets in year 8 and I'm still making stupid mistakes! DOH!
0
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