# Math Help - SAT Problem

1. ## 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

2. 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

3. 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

4. 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 $(n - 2)180^\circ$, where $n$ is the number of sides.

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

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

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

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