Answer: y = 2x^4
The graph represents a parabolic-looking shape so it's either a quadratic or some even degree polynomial. This rules out y = -2x^3 and y = 2x^3 as they are cubics with odd degrees
The degree of a polynomial is the largest exponent. It determines the end behavior. In this case, both ends are rising upward together. Because they are rising up in the positive y direction, this means that we cannot have y = -2x^4 as the answer. For example, if x = 2 then y = -2*x^4 = -2*2^4 = -32, but the point (x,y) = (2,-32) isn't on the blue curve. So we can rule y = -2x^4 out.
The fact that y = 2x^4 has a positive leading coefficient tells us that the endpoints point upward.
A)
B)
C)
D)
You were correct, the exact answer is A. The others do not equal 23 besides that one. Good job!
The sum is 160/(1-r)=1280 where r is the common ratio,
1/(1-r)=1280/160=8
Inverting we get 1-r=1/8, r=7/8.
