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2002 Winter Diet - non calc - HSN forum # 2002 Winter Diet - non calc

### #1broxibabi

• Gender:Female

Posted 18 May 2004 - 09:28 PM

Hey,id appreciate it if someone could give me a help with these! I got 64%(is that any good?!)for the paper but I still can't do these two questions at all:

(10) A function f is defined by f(x)=2x+3+18/x-4 x does not equal 4
Find the values of x for which the function is increasing.

(12) If logap=cossquaredx and logar=sinsquaredx, show that pr=a

Thanx very much if anyone can help! ### #2AndyW

• Gender:Not Telling

Posted 18 May 2004 - 09:54 PM

10.

You can write the function as f(x) = 2x + 3 + 18(x-4)^-1

Differentiate the function to get:

f'(x) = 2 - 18(x-4)^2

Set this equal to 0 and solve for x to find the stationary points.

Use a nature table to find where it increasing.

12.

log_a p = cos squared x
so p = a^(cos squared x)

log_a r = sin squared x
so r = a^(sin squared x)

Then

pr = a^(cos squared x)a^(sin squared x)
pr = a^(cos squared x + sin squared x) [note the trig identify]
pr = a^1
pr = a

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