# SAT Problem

• Jan 19th 2010, 03:32 AM
juliak
SAT Problem
If g(x) = x * 2^x, then g(a+1) - g(a)=
(a) (a+2)2^a
(b) (2a+1)2^a
(c) (2a-1)2^1
(d) (a+1)2^a+1
(e) (a)2^a+1
• Jan 19th 2010, 04:24 AM
CaptainBlack
Quote:

Originally Posted by juliak
If g(x) = x * 2^x, then g(a+1) - g(a)=
(a) (a+2)2^a
(b) (2a+1)2^a
(c) (2a-1)2^1
(d) (a+1)2^a+1
(e) (a)2^a+1

Try some values for a and see which cases are possible. For example if a=0

g(a+1)-g(a)=g(1)-g(0)=2

and (a)=2, (b)=1, (c)=-2, (d)=2, (e)=1

so we have elliminated all but (a) and (d), now try another value.

CB
• Jan 19th 2010, 04:52 AM
juliak
Thank you very very much!

(sorry but) another question I have:

Which of the following CANNOT represent the degree measure of an equiangular polygon?
(a) 165
(b) 162
(c) 140
(d) 125
(e) 90
• Jan 19th 2010, 05:06 AM
Prove It
Quote:

Originally Posted by juliak
Thank you very very much!

(sorry but) another question I have:

Which of the following CANNOT represent the degree measure of an equiangular polygon?
(a) 165
(b) 162
(c) 140
(d) 125
(e) 90

The internal sum of a polygon is given by $\displaystyle (n - 2)180^\circ$, where $\displaystyle n$ is the number of sides.

If it is a regular polygon then all the angles are equal. Since you have $\displaystyle n$ angles, then if $\displaystyle \theta$ is one of the angles

$\displaystyle n\theta = (n - 2)180^\circ$.

So $\displaystyle \theta = \frac{(n - 2)180^\circ}{n}$.

So now substitute some values for $\displaystyle n$ and see which ones that you have listed apply.