need some help with this one guys..

y=2sin(3x + pi) -1

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- Sep 8th 2009, 09:23 AMfezz349Domain & range of trig function
need some help with this one guys..

y=2sin(3x + pi) -1 - Sep 8th 2009, 09:36 AMred_dog
First of all use the formula $\displaystyle \sin(\pi+x)=-\sin x$.

Then $\displaystyle y=-2\sin 3x-1$

The domain is $\displaystyle \mathbb{R}$.

We have $\displaystyle -1\leq\sin 3x\leq 1\Rightarrow -2\leq -2\sin 3x\leq 2\Rightarrow -3\leq -2\sin 3x-1\leq 1$

So the range is $\displaystyle [-3,1]$ - Sep 8th 2009, 09:50 AMfezz349
thanks a lot bro, btw, does the R in the domain mean all rea numbers?

- Sep 8th 2009, 02:05 PMTKHunny
You got it. The fancy "R" does, indeed, mean The Real Numbers. Guess what a fancy "N" means?